Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq

Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq Hassan A. Aljaberi, Saeed Rahmani, Amel Muhson Naji This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5477082/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Sep, 2025 Read the published version in BMC Ophthalmology → Version 1 posted 8 You are reading this latest preprint version Abstract Purpose To establish the relationship between ocular biometry and refractive errors in young adult Iraqis by analyzing three critical biometric ocular parameters, including axial length (AL), corneal radius (CR), and central corneal thickness (CCT). Methods A cross-sectional analysis of individuals aged 18-33 years was conducted at Al-Mustaqbal University, Iraq, yielding 1841 participants (3682 eyes). Quantitative data on AL, CR, and CCT were obtained by an Auto Kerato-Refractometer, IOL Master and pachymetry techniques. We used Pearson correlation coefficients to measure the correlation between AL, CR, CCT, and refractive errors (myopia, hyperopia, astigmatism). Gender differences and interactions with these correlations were also examined. Results In total, Mean AL was 24.45 ± 1.10 mm; CR was 7.37 ± 0.77 mm; and CCT was 555.83 ± 50.83 µm. Myopic participants had a statistically significantly more significant mean AL of 25.11 ± 0.42 mm than the hyperopic subjects, with a mean AL of 22.71 ± 0.65mm (p < 0.001). Females had slightly longer ALs on average than males in myopic and hyperopic groups of eyes. Myopic individuals also exhibited thicker corneas (mean CCT: 565.62 ± 12.68 µm) compared to hyperopic individuals (mean CCT: 495.42 ± 18.74 µm). Indeed, AL and CCT were significantly related to refractive error, and these findings affirmed AL as a dominant predictor. Conclusions This self-gathered outcome resolved alterations AL as a chief contributing factor of refractive mistake; it links with important differentiations partly by sex. The findings of the study help fill existing gaps in the knowledge base and shape future public health interventions aimed at addressing refractive errors among young adults in Iraq. Refractive errors Biometric ocular parameters Students university Iraq Cross-sectional study Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 1. Introduction Biometric ocular measures, including axial length (AL), corneal radius (CR), and central corneal thickness (CCT), are essential in assessing the refractive state of the eye. Variations in these biometric characteristics are strongly associated with an increase of refractive errors, including myopia, hyperopia, and astigmatism. For instance, an elongated axial length is often correlated with myopia, while a shorter axial length typically results in hyperopia. The amount of refractive error is affected by the cornea's shape and thickness, which in turn affect the retina's ability to focus light. Based on the prevalence and influence on quality of life, research shows that refractive errors continue to be a major public health concern [ 1 – 3 ]. About 157 million people across the globe have difficulties seeing because their refractive defects have not been corrected, according to the World Health Organization (WHO) [ 4 ]. When the eye is unable to properly focus light onto the retina, an inaccurate image is formed, leading to refractive errors [ 5 ]. A number of abnormalities in ocular biometric parameters, including axial length, corneal curvature, central corneal thickness, and the lens, contribute to refractive errors such myopia, hyperopia, and astigmatism [ 5 – 8 ]. Research shows that understanding these eye biometric variables is crucial for developing plans to control and avoid refractive errors [ 9 – 10 ]. Ocular biometrics and refractive errors were reported in several studies focusing on Iran. In Tehran, Hashemi et al. [ 11 ] found that the mean axial length was significantly longer in myopic eyes than in emmetropic and hyperopic eyes. The overall prevalence of myopia was estimated to be 21.8% among participants aged 40 to 64, which is an emerging public health problem. Fu et al. [ 12 ] reported a myopia prevalence of 4.4% among school-going children; this suggests that geographical and lifestyle factors influence refractive error development. This has also been furthered by research into the aspects of ocular biometrics related to refractive errors contributed by Mukazhanova et al. [ 13 ] documented myopia to be at 25.3% among university students in Kazakhstan, and Wang et al. [ 14 ] at 53.7% among high school students in eastern China. The present findings support previous literature regarding the rising prevalence of myopia in the urban and educated populations, as documented by Philip et al. [ 15 ] in the analysis of refractive errors in South Indian adults. The better ophthalmic health infrastructure in Saudi Arabia has enabled it to study myopia in greater detail [ 16 – 19 ]. Wang et al. [ 14 ] estimated the prevalence of myopia and reported that 34.5% of high school students in eastern China, are myopic did not wear glasses. Indeed, a significant association of higher axial length was noted, associated with myopic refractive error. Some studies identified urbanization and socioeconomic factors in the variation of the prevalence of refractive errors, observing a higher prevalence in places where near-work activities were more usual in urban settings [ 15 , 20 – 22 ]. A comparison of these studies indicates that genetic predisposition factors occur in refractive errors, but environmental and lifestyle factors are essential contributors in the Middle East [ 23 ]. The prevalence of myopia indeed differs in neighboring countries, being higher than its rates in other more urbanized regions and where the engagement in near-work activities is higher [ 24 – 25 ]. Myopic individuals' mean axial length is invariably more extended than emmetropic and hyperopic individuals; thus, it is an essential biometric marker [ 26 – 28 ]. While numerous studies have explored the relationship between biometric parameters and refractive errors globally, research in the Middle East and particularly Iraq remains limited [ 18 , 29 ]. This gap in knowledge is significant given the unique sociocultural, genetic, and environmental factors in Iraq that may influence the development of refractive errors. To address the rising public health concern of uncorrected refractive defects, shape future therapies, and contribute significant data to the worldwide ophthalmic knowledge base, it is crucial to understand these linkages. Prior research in nearby nations like Saudi Arabia and Iran found strong links between axial length (AL) and refractive errors; variations in these relationships were explained by environmental, genetic, and socioeconomic variables. [ 30 – 32 ]. To address this gap, researchers at Iraq's Al-Mustaqbal University examined the relationship between biometric ocular characteristics and refractive errors in college students and staff. Lifestyle factors, such as restricted outside exposure and prolonged near-work activities, have been associated with the development of myopia, putting university students at a higher risk for refractive errors. This study will help provide insight on the biometric factors that lead to refractive errors in the Iraqi population by addressing a data gap in the region. Also, it will serve as the groundwork for public health initiatives in the future that aim to control and prevent refractive defects in young people, a group that is becoming more vulnerable as a result of contemporary lifestyle choices. 2. Subjects and Methods 2.1. Subjects This study was carried out at Al-Mustaqbal University in Iraq during the 2023–2024 academic year. A total of 1,841 subjects were enlisted, encompassing 3,682 eyes, with ages ranging from 18 to 33 years. The majority of participants were female (57.77%, n = 2127), whereas males comprised 42.23% (n = 1555). The overall mean age was 22.21 ± 3.41 years. The sample size (n = 3682 eyes) was determined based on an a priori statistical power analysis to detect small to moderate effect sizes (Cohen’s d = 0.2–0.5) with 80% power and a 95% confidence level. The relatively large sample size was intended to enhance the robustness and reliability of the results. While the sample was drawn from a university population, this group represents a critical demographic where refractive errors are increasingly prevalent due to environmental and lifestyle factors. Nonetheless, we acknowledge that the sample may not fully capture the diversity of the broader Iraqi young adult population. This limitation is noted in the discussion, and future research should include broader geographic and socioeconomic representation to enhance generalizability. Participants were selected based on clear inclusion and exclusion criteria. All subjects were required to be students or employees at Al-Mustaqbal University at the time of data collection. Participants with a history of ocular surgery, systemic diseases (e.g., diabetes), ocular trauma, or unrelated eye conditions were excluded. Only individuals with stable ocular health were included to avoid factors that could affect refractive outcomes. Figure 1 shows the distribution of participants' eyes by age group and gender. Younger individuals, particularly in the 18–21 and 22–25 age groups, were more represented, which is reflective of typical university demographics. This trend aligns with typical university demographics, where female participation may be higher in certain disciplines. Separating participants by gender and age helps reduce bias and facilitates more accurate comparisons of biometric measurements across different groups. 2.2. Examinations and Assessments Detailed ophthalmologic examinations were conducted on all 1841 individuals, resulting in a total of 3682 eyes examined. Refraction was assessed using automated refraction followed by subjective refinement to determine the spherical equivalent refractive error for each eye. Axial length (AL) was measured using a non-contact IOL Master, which provides high-precision ocular biometry. Corneal curvature was measured using the Topcon KR-800 Auto Kerato-Refractometer. Central corneal thickness (CCT) was measured using an ultrasonic pachymeter, which was specifically selected due to its clinical accuracy, portability, and proven reliability across diverse patient groups. While the IOL Master does offer a corneal thickness measurement function, in our setting it was not available with the upgraded CCT module. Furthermore, the ultrasonic pachymeter has been validated in multiple studies for precise corneal thickness assessment and remains a gold-standard method in many clinical contexts. The devices used were the latest models available in our university laboratories and were regularly calibrated and maintained by certified optometrists and ophthalmologists to ensure measurement precision. This method allowed us to capture accurate biometric data suitable for robust statistical analysis. Furthermore, anthropometric measurements, encompassing ocular biometrics, were collected, succeeded by additional assessments to investigate the relationships between ocular dimensions and other ophthalmological parameters pertinent to refractive errors. This thorough methodology offered a detailed perspective on the ocular health status of the study population. 2.3. Definitions Refractive error (RE) is categorized according to the spherical equivalent (SE), ascertained by aggregating the spherical value with half of the cylindrical value. Myopia or nearsightedness is defined by a spherical equivalent (SE) of ≥ -0.50 diopters (D). Mild to moderate myopia is defined as ranging from − 0.50D to -6.00D, but severe myopia is characterized by a spherical equivalent above − 6.00D. Hyperopia, or farsightedness, is defined by a spherical equivalent (SE) of ≥ + 0.50 diopters (D). Astigmatism is defined as a cylindrical refractive error of ≥ 0.50 diopters, irrespective of the spherical equivalent. These classifications align with recommendations from prominent ophthalmologic conferences and generally recognized research. Axial length (AL) is the measurement from the corneal surface to the retina, significantly influencing refractive errors. An elongated axial length (AL) is linked to myopia, whereas a shortened AL is connected with hyperopia. The corneal radius (CR) denotes the curvature of the cornea; anomalies in CR are associated with astigmatism and other refractive disorders. center corneal thickness (CCT) quantifies the thickness of the cornea's center region and is crucial for evaluating intraocular pressure and refractive disorders, including glaucoma. 2.4. Data Analysis SPSS version 26.0 (SPSS Corp., Chicago, USA) was used to evaluate the data. The spherical equivalent (SE) and axial length (AL) of each eye were measured objectively on all of the patients. The Kolmogorov-Smirnov test was used to see if the distributions of SE, AL, corneal, central corneal thickness (CCT), and radius (CR) were normal in both men and women. A significance level of p < 0.05 meant that the distributions were normal. We used Pearson correlation coefficients to look at the connections between AL, CCT, CR, and SE for both male and female subjects. A p value of less than 0.001 was used to determine statistical significance. To account for differences between people, the study used measurements from both the right and left eyes. Paired samples t-tests with a significance level of p < 0.05 were used to compare SE and AL by gender. One-way analysis of variance (ANOVA) was used to compare changes in axial length between groups of refractive error. The study focused on mild myopia, hyperopia, and astigmatism. We used the least significant difference (LSD) test to find significant group differences in post hoc studies. For inter-group comparisons, a p-value of less than 0.001 was considered statistically significant. The data are shown as the mean ± the standard deviation, along with 95% confidence ranges. Because there were a lot more women than men who participated, most of the studies were done with subgroups of people of the same gender. Box plots and tables show descriptive terms like AL, CR, CCT, and SE so that they can be compared across different types of refractive error. 3. Results 3.1. Biometric Parameters and Refractive Error Distribution The mean axial length (AL) for all individuals was 24.45 ± 1.10 mm, the mean corneal radius (CR) was 7.37 ± 0.77 mm, and the mean central corneal thickness (CCT) was 555.83 ± 50.83 µm. Table 1 delineates the average ocular biometric data categorized by type of refractive error. Deviations in corneal curvature in myopic and hyperopic patients presumably arise from a confluence of genetic, environmental, developmental, and measurement-related factors. These variances are crucial for comprehending the complete intricacy of refractive defects and their clinical therapy. The clinical interpretation of refractive error data is constrained without a thorough examination of the interaction between corneal curvature and axial length in these patients. Table 1 Mean ocular biometric measurements stratified by refractive error type, including AL, CR, and CCT. Refractive Error N AL Mean ± SD (mm) CR Mean ± SD (mm) CCT Mean ± SD (µm) Myopia 1871 25.11 ± 0.42 6.86 ± 0.44 565.62 ± 12.68 Hyperopia 626 22.71 ± 0.65 8.53 ± 0.38 495.42 ± 18.74 Astigmatism 1185 24.31 ± 0.96 7.54 ± 0.58 530.93 39.94 3.2. Correlation Analyses To examine the correlations between various biometric parameters, scatter plots have been constructed to understand their interaction with refractive errors. Figure 2 illustrates a notable negative correlation between axial length (AL) and corneal radius (CR), emphasizing the compensatory link between these parameters in sustaining refractive equilibrium. The results indicate that myopia is influenced not only by axial length elongation but also by corneal steepening (reduced curvature radius), which increases refractive power. Likewise, hyperopia results from a conjunction of reduced axial length and a flatter cornea (elevated curvature radius). These studies highlight the interconnected relationship between axial length (AL) and corneal radius (CR) in the progression of refractive error. The moderate correlation strength indicates that additional factors, such as lens thickness and anterior chamber depth, contribute to refractive outcomes. Figure 3 depicts the correlation between axial length (AL) and central corneal thickness (CCT), showing an extremely strong positive association (r = 0.88, p < 0.001). As AL rises, CCT rises proportionally. Figure 4 illustrates the relationship between central corneal thickness and corneal radius, revealing a moderate negative association (r = -0.577, p < 0.001). As CCT declines, CR rises. Figure 5 illustrates the association between spherical equivalent and central corneal thickness, demonstrating an extremely strong negative correlation (r = -0.883, p < 0.001). As SE declines, CCT escalates. Figure 6 illustrates a moderate positive correlation between corneal curvature radius (CR) and spherical equivalent (SE), highlighting the critical role of corneal curvature in shaping refractive power. 3.3. Gender Differences in Biometric Parameters Figure 7 shows the distribution of ALs by sex, revealing that females tended to have longer axial lengths (25.35 ± 0.50 mm) than males did (24.95 ± 0.61 mm), which was a statistically significant difference (p < 0.001). 3.4. Prevalence of Refraction Errors and Ocular Biometric Parameters by Gender Figure 8 illustrates the prevalence of refraction errors categorized by sex. Myopia and astigmatism were more prevalent in females, while hyperopia showed a similar distribution across sexes. 3.5. Ocular Biometric Differences by Refractive Error Group Figure 9 shows the eyes with shorter ALs (25 mm) were associated with myopia. Figure 10 shows the myopic eyes had the longest ALs (24–26 mm), while hyperopic eyes had the shortest (<23 mm). 3.6. Central Corneal Thickness and Corneal Radius Across Refractive Error Groups Figure 11 shows the myopic eyes had the thickest CCT (550–600 µm), while hyperopic eyes had the thinnest (<500 µm). Figure 12 shows the myopic eyes had the steepest corneas (6.5–7.5 mm CR), and hyperopic eyes had the flattest (8.0–9.0 mm CR). Figure 13 shows the p-values for axial length, corneal radius, and central corneal thickness across different age groups. The p-values for axial length are particularly low in the 18–21 age group, indicating significant variation in axial length with age. For the corneal radius, the p-values remain below the significance threshold but increase with age. The statistical significance of central corneal thickness decreases with age but remains relevant. 3.7. Analysis of biometric ocular parameters across refractive error groups and gender differences Ocular biometric characteristics axial length, corneal radius, and central corneal thickness are compared across myopic, hyperopic, and astigmatic refractive error groups. A gender-based breakdown is also provided to analyze differences between male and female participants within each refractive error group. Table 2 One-way ANOVA for biometric ocular parameters among refractive error groups Parameter F-statistic p-value Axial Length F(2, 3697) = 2967 p < 0.001 Corneal Curvature F(2, 3697) = 2936 p < 0.001 Central Corneal Thickness F(2, 3697) = 1944 p < 0.001 Table 2 presents the findings of the one-way analysis of variance (ANOVA) for biometric ocular parameters across refractive error categories (p < 0.001). Table 3 Mean axial length by refractive error and gender Male Female Refractive Error N Mean ± SD 95% CI N Mean ± SD 95% CI p-value Myopia 739 25.04 ± 0.42 25.01 - 25.07 1132 25.15 ± 0.41 25.13 - 25.18 < 0.0001 Hyperopia 317 22.60 ± 0.64 22.53 - 22.68 309 22.82 ± 0.64 22.74 - 22.89 < 0.0001 Astigmatism 499 24.17 ± 0.96 24.09 - 24.26 686 24.42 ± 0.95 24.35 - 24.49 < 0.0001 Table 3 compares axial length (AL) between males and females within each refractive error group. Females consistently exhibit significantly longer ALs than males across all groups (p < 0.0001). Table 4 Pairwise comparisons of axial length by refractive error groups Group 1 Group 2 Mean Difference 95% CI p-value Myopia Astigmatism 0.794 0.736 - 0.852 < 0.0001 Myopia Hyperopia 2.399 2.345 - 2.454 < 0.0001 Astigmatism Hyperopia 1.606 1.531 - 1.681 < 0.0001 Table 4 presents axial length comparisons within each refractive error group and overall, using the LSD method. Significant differences were observed: myopic participants had a greater axial length than astigmatic participants (mean difference: 0.794 mm, p < 0.0001) and hyperopic participants (mean difference: 2.399 mm, p < 0.0001). Astigmatic eyes also exhibited a longer axial length than hyperopic eyes (mean difference: 1.606 mm, p < 0.0001). Table 5 Mean axial length (AL) by spherical equivalent (SE) range and sex Group SE Male Female N Mean AL ± SD 95% CI N Mean AL ± SD 95% CI p-value 1 -0.50 to -2.00 519 24.64 ± 0.25 24.62 - 24.66 769 24.82 ± 0.22 24.81 - 24.84 < 0.0001 2 -2.25 to -4.00 456 25.28 ± 0.20 25.26 - 25.30 666 25.44 ± 0.23 25.43 - 25.46 < 0.0001 3 -4.25 to -6.00 53 25.95 ± 0.25 25.89 - 26.02 72 26.13 ± 0.29 26.06 - 26.20 = 0.0003 4 +0.50 to +2.00 280 23.31 ± 0.38 23.26 - 23.35 350 23.57 ± 0.43 23.52 - 23.61 < 0.0001 5 +2.25 to +4.00 247 22.32 ± 0.46 22.26 - 22.38 270 22.64 ± 0.50 22.58 - 22.70 < 0.0001 Table 5 summarizes axial length (AL) by sex and spherical equivalent (SE) range, showing significant sex differences across all SE groups. Females consistently exhibit longer AL than males, including in the SE range -0.50 to -2.00 (females: 24.82 ± 0.22 mm; males: 24.64 ± 0.25 mm, p < 0.0001), -2.25 to -4.00 (females: 25.44 ± 0.23 mm; males: 25.28 ± 0.20 mm, p < 0.0001), and -4.25 to -6.00 (females: 26.13 ± 0.29 mm; males: 25.95 ± 0.25 mm, p = 0.0003). Discussion This study clarifies the relationship between biometric ocular characteristics and refractive errors in participants from Al-Mustaqbal University in Iraq. Fan et al. [33] identified a comparable tendency, noting a substantial association between axial length (AL) and refractive error in university students of Chinese descent, with myopes demonstrating greater AL than hyperopes or emmetropes. These results contribute to the existing literature on ocular biometrics and refractive errors, especially within Middle Eastern populations. The gender differences observed in our study have implications for clinical practice and public health policies. Our results indicate that females tend to develop certain types of refractive errors, such as myopia and astigmatism, at a younger age than males. This aligns with Zeried et al.'s findings [19] on gender-sensitive attitudes towards refractive correction among Saudi students. Recognizing these gender-specific dynamics is crucial for developing effective therapies and prevention strategies, particularly for young women who are at a higher risk of developing severe myopia. Compared with male participants, females generally had longer axial lengths across various refractive error and SE categories, a trend that differs from that of Fan et al. [33], who reported that Chinese male students had longer ALs. Our findings suggest that genetic and environmental factors may play a significant role in determining axial length (AL) in females, particularly in cases of high myopia. Females consistently exhibited longer ALs than males across various refractive error groups and spherical equivalent (SE) ranges, as shown in the study. This trend was especially evident in high myopia, such as in the -4.25 to -6.00 SE range, where females had significantly longer ALs (26.13 ± 0.29 mm) compared to males (25.95 ± 0.25 mm, p = 0.0003). These differences may be influenced by genetic and hormonal factors, as well as lifestyle elements such as increased near-work activities and reduced outdoor exposure, which are more common among females in specific demographic groups. Together, these findings emphasize the pivotal role of genetic and environmental factors in shaping AL, particularly in females with high myopia. The study also revealed a strong correlation between the AL and refractive error. Longer ALs are associated with myopia, reinforcing the well-established concept that eye elongation exacerbates myopia, with a focus on light in front of the retina. Conversely, hyperopic eyes had shorter ALs, causing light to focus behind the retina, resulting in farsightedness. These observations support previous research, such as the Tehran Geriatric Eye Study by Hashemi et al. [11], and are consistent with findings from Bikbov et al. [6], who explored similar patterns in children and adolescents. Central corneal thickness (CCT) has been shown to correlate with refractive status, particularly in myopic individuals. The study confirms that myopic eyes tend to have thicker corneas compared to hyperopic eyes. This may serve as a compensatory mechanism to maintain structural integrity as axial length (AL) increases in myopic eyes. Increased AL can create additional stress on the ocular structures, and a thicker cornea may help prevent distortion and deformation under higher intraocular pressure, which is more commonly observed in myopia. However, not all studies align with this finding. For instance, Almazrou et al. [34], reported no significant differences in CCT between myopic and non-myopic individuals, suggesting variability in CCT’s relationship with myopia. This discrepancy highlights the need for further research to better understand how CCT interacts with different degrees of myopia and other ocular parameters. These CCT differences have important implications for patient management, particularly in refractive surgeries, as noted by Khoramnia et al. [7]. While CCT is typically thicker in myopic individuals, it does not appear to change significantly with minor shifts in refractive status. Instead, its relationship with refractive errors may reflect broader compensatory adaptations in highly myopic eyes. It remains unclear if CCT itself contributes directly to refractive error progression or is merely a consequence of structural adjustments related to AL elongation. This area warrants further investigation, particularly in longitudinal studies that can track changes in CCT and refractive error development over time. CCT tends to decrease with age, a pattern well-documented in various populations. This thinning is believed to result from biomechanical and biochemical changes in the corneal stroma, such as a reduction in collagen density and hydration levels. Older adults generally exhibit thinner corneas, which could have implications for refractive error stability and intraocular pressure measurements, as thinner corneas may lead to underestimation of intraocular pressure. This age-related thinning may also partially explain differences in refractive error patterns between younger and older populations, as thinner corneas may contribute to changes in refractive stability. A moderate negative correlation was observed between central corneal thickness (CCT) and corneal radius (CR) (r = -0.577, p < 0.001), indicating that thinner corneas are associated with flatter curvature. This relationship underscores the biomechanical interplay between corneal thickness and curvature, particularly in myopic eyes. Thinner corneas may contribute to reduced structural rigidity, leading to compensatory flattening of the cornea. These findings are clinically significant for assessing refractive error progression, surgical planning, and identifying early signs of corneal instability. There are several limitations to this study. Since it focused on healthy university students, the findings may not be generalizable to other populations, such as older adults or children, who may exhibit different refractive error patterns. Additionally, the cross-sectional nature of the data makes it challenging to assess changes in refractive errors over time. Future longitudinal research should explore these trends further and investigate how genetic and environmental factors contribute to sex differences in AL. More research is needed to understand the role of CCT in postsurgical patients, especially those who have undergone corneal refractive surgery. Changes in CCT provide critical information when performing refractive surgeries such as LASIK or photorefractive keratectomy. Corneal thickness should be assessed with refractive error prior to planning surgical treatments, particularly for patients who have major myopia or hyperopia. This matches Alrashidi's study [35] about the impact of elimination depth on endothelial health in Saudi patients undergoing photorefractive keratectomy. Our findings could help specialists in adjusting their techniques based on patient features, potentially reducing adverse surgical outcomes. The results of this study require more investigation, particularly concerning the lasting influence of genetic and environmental factors on gender differences in AL. The hypothesized importance of the ocular surface bacteria in the emergence of refractive error necessitates additional research. [36]. Recent studies suggest that an imbalance in the ocular surface microbiome may trigger inflammatory responses and biomechanical degradation of the cornea, particularly influencing parameters such as central corneal thickness (CCT) and corneal curvature (CR). These abnormalities may exacerbate myopia progression or result in conditions like as keratoconus, which is marked by anomalies in corneal curvature. Given the increasing prevalence of myopia and its association with environmental and lifestyle factors, more investigation into the ocular microbiome may provide valuable insights into the pathogenesis of refractive defects and uncover novel therapeutic or preventive strategies. Moreover, further research is required to examine the relationship between CCT and refractive outcomes in post-surgical patients, since this may significantly impact long-term treatment strategies [37]. In conclusion, our research underscores the importance of biometric ocular factors such as axial length, corneal curvature, and central corneal thickness in evaluating refractive status. These findings corroborate and enhance prior research carried out in nearby regions and globally. Our findings suggest that female students may be more susceptible than male students to severe refractive errors, particularly myopia, underscoring the necessity for gender-sensitive strategies for addressing this problem. As urbanization and lifestyle changes continue to impact refractive error prevalence in the Middle East and worldwide, our findings contribute valuable knowledge that can inform public health and clinical strategies for addressing this significant health concern. This study’s insights have direct applications in patient management and public health, as uncorrected refractive errors remain one of the leading causes of visual impairment globally. Declarations Acknowledgements The authors sincerely thank the Deanship of the College of Health and Medical Techniques at Al-Mustaqbal University for their valuable assistance in data collection. Authors’ contributions Hassan A. Aljaberi and Saeed Rahmani conceived and supervised the experiment and also conducted the study. Amal Mohsen Naji collected and analyzed the data. Hassan A. Aljaberi drafted the manuscript, while Saeed Rahmani revised it. All authors read and approved the final manuscript. Funding Not Applicable. Accessibility of resources and data The data supporting the findings of this investigation are accessible in the supplemental material of this publication. Approval of ethics and consent for participation All procedures were conducted in compliance with the ethical norms established by the institutional and national research committees, in addition to the Declaration of Helsinki. The Research Ethics Committee of the Faculty of Health and Medical Techniques of Al-Mustaqbal University accepted this study on 23/09/2023 (reference number 23092023). All study participants provided informed consent to participate. Authorization for publication Not Applicable. Competing interests The authors assert that they possess no competing interests. Authors details 1 Optics Techniques Department, College of Health and Medical Techniques, Al-Mustaqbal University, 51001, Hillah, Iraq 2 Department of Optometry, Faculty of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Department of Optics Techniques, Dijlah University College, Al-Masafi Street, Al-Dora, Baghdad, 00964, Iraq Data Availability The date that supports the findings of this study are available in the supplementary material of this article. References Hashemi A, Khabazkhoob M, Hashemi H. High prevalence of refractive errors in an elderly population; a public health issue. BMC Ophthalmol. 2023;23(1):38. Magakwe TS, Hansraj R, Xulu-Kasaba ZN. The impact of uncorrected refractive error and visual impairment on the quality of life amongst school-going children in Sekhukhune district (Limpopo), South Africa. Afr Vis Eye Health. 2022;81(1):7. Pirindhavellie G-P, Yong AC, Mashige KP, Naidoo KS, Chan VF. The impact of spectacle correction on the well-being of children with vision impairment due to uncorrected refractive error: a systematic review. BMC Public Health. 2023;23(1):1575. Study VLEGotGBoD. Global estimates on the number of people blind or visually impaired by Uncorrected Refractive Error: a meta-analysis from 2000 to 2020. Eye. 2024;38(11):2083. Nser HY, Al-Sharify NT, Ahmed SM, Weng LY, See OH, Al-Sharify ZT, et al. editors. Review study of refraction error measurement methods of human cornea. AIP Conference Proceedings; 2023: AIP Publishing. Bikbov MM, Kazakbaeva GM, Fakhretdinova AA, Tuliakova AM, Iakupova EM, Panda-Jonas S, et al. Associations between axial length, corneal refractive power and lens thickness in children and adolescents: The Ural Children Eye Study. Acta Ophthalmol. 2024;102(1):e94–104. Khoramnia R, Auffarth G, Łabuz G, Pettit G, Suryakumar R. Refractive outcomes after cataract surgery. Diagnostics. 2022;12(2):243. Ng’andu A, Krikor E, Mutati GC. Variations in Ocular Biometrics Related to Refractive Errors Among Adult Patients Attending the University Teaching Hospitals-Eye Hospital in Lusaka, Zambia. Anat J Afr. 2022;11(1):2092–101. Benzir M, Afroze A, Zahan A, Naznin RA, Khanam A, Sumi SA et al. A study linking axial length, corneal curvature, and Eye Axis with demographic characteristics in the emmetropic eyes of Bangladeshi people. Cureus. 2022;14(10). Fan Y, Wang J, Lei J, Ji J, Xie P, Hu Z. Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia. Graefe's Archive Clin Experimental Ophthalmol. 2024:1–12. Hashemi H, Heydarian S, Hashemi A, Khabazkhoob M. Axial length and anterior chamber indices in elderly population: Tehran Geriatric Eye Study. Int J Ophthalmol. 2023;16(11):1876. Fu A, Watt K, Junghans M, Delaveris B, Stapleton A. Prevalence of myopia among disadvantaged Australian schoolchildren: A 5-year cross-sectional study. PLoS ONE. 2020;15(8):e0238122. Mukazhanova A, Aldasheva N, Iskakbayeva J, Bakhytbek R, Ualiyeva A, Baigonova K, et al. Prevalence of refractive errors and risk factors for myopia among schoolchildren of Almaty, Kazakhstan: A cross-sectional study. PLoS ONE. 2022;17(6):e0269474. Wang J, Ying G-s, Fu X, Zhang R, Meng J, Gu F, et al. Prevalence of myopia and vision impairment in school students in Eastern China. BMC Ophthalmol. 2020;20:1–10. Philip K, Sankaridurg P, Naduvilath T, Konda N, Bandamwar K, Kanduri S, et al. Prevalence and patterns of refractive errors in children and young adults in an urban region in south India: The Hyderabad eye study. Ophthalmic Epidemiol. 2023;30(1):27–37. Al Nahedh T. Current Concepts of Myopia, Etiology, and Recent Treatments in Saudi Arabia. J Health Inf Developing Ctries. 2023;17(01). Alghamdi W, Ovenseri-Ogbomo GO. The prevalence and causes of visual impairment in Dariyah, a rural community in Saudi Arabia. Afr Vis Eye Health. 2021;80(1):5. Alrasheed SH, Aldakhil S. Corneal curvature, anterior chamber depth, lens thickness, and vitreous chamber depth: Their intercorrelations with refractive error in Saudi adults. Open Ophthalmol J. 2022;16(1). Zeried FM, Alnehmi DA, Osuagwu UL. A survey on knowledge and attitude of Saudi female students toward refractive correction. Clin Experimental Optometry. 2020;103(2):184–91. Biswas S, El Kareh A, Qureshi M, Lee DMX, Sun C-H, Lam JS, et al. The influence of the environment and lifestyle on myopia. J Physiol Anthropol. 2024;43(1):7. Hung HD, Chinh DD, Tan PV, Duong NV, Anh NQ, Le NH et al. The Prevalence of myopia and factors associated with it among secondary school children in rural Vietnam. Clin Ophthalmol. 2020:1079–90. Philip K, Paudel P, Vincent J, Marmamula S, Fricke T, Sankaridurg P. Refractive Error and School Eye Health. South-East Asia Eye Health: Systems, Practices, and Challenges. Springer; 2021. pp. 145–68. Khoshhal F, Hashemi H, Hooshmand E, Saatchi M, Yekta A, Aghamirsalim M, et al. The prevalence of refractive errors in the Middle East: a systematic review and meta-analysis. Int Ophthalmol. 2020;40:1571–86. Lee SS, Mackey DA. Regional Differences in Prevalence of Myopia: Genetic or Environmental Effects? Advances in Vision Research, III: Genetic Eye Research around the Globe. 2021:365–79. Morgan IG, Wu P-C, Ostrin LA, Tideman JWL, Yam JC, Lan W, et al. IMI risk factors for myopia. Investig Ophthalmol Vis Sci. 2021;62(5):3–3. Assi L, Chamseddine F, Ibrahim P, Sabbagh H, Rosman L, Congdon N, et al. A global assessment of eye health and quality of life: a systematic review of systematic reviews. JAMA Ophthalmol. 2021;139(5):526–41. Gong X, Wu X-H, Liu A-L, Qian K-W, Li Y-Y, Ma Y-Y, et al. Optic nerve crush modulates refractive development of the C57BL/6 mouse by changing multiple ocular dimensions. Brain Res. 2020;1726:146537. Rozema J, Dankert S, Iribarren R. Emmetropization and nonmyopic eye growth. Surv Ophthalmol. 2023;68(4):759–83. Rattan SA, Ridha RM, Majeed BQ, Hussien ZZ, Abdullah NA. Awareness and Knowledge About RefractiveSurgery Among Medical Students in Baghdad. Pakistan J Ophthalmol. 2024;40(2). Alexopoulos P, Madu C, Wollstein G, Schuman JS. The development and clinical application of innovative optical ophthalmic imaging techniques. Front Med. 2022;9:891369. Kam KW, Pang CP, Yam JC. Refractive Errors, Myopia, and Presbyopia. Ophthalmic Epidemiol. 2022:87–112. Lazreg S, Hosny M, Ahad MA, Sinjab MM, Messaoud R, Awwad ST et al. Dry Eye Disease in the Middle East and Northern Africa: a position paper on the current state and unmet needs. Clin Ophthalmol. 2024:679–98. Fan Q, Wang H, Jiang Z. Axial length and its relationship to refractive error in Chinese university students. Contact Lens Anterior Eye. 2022;45(2):101470. Almazrou AA, Abualnaja WA, Abualnaja AA, Alkhars AZ, Abualnaja W, Abualnaja A. Central corneal thickness of a Saudi population in relation to age, gender, refractive errors, and corneal curvature. Cureus. 2022;14(10). Alrashidi SH. Effect of Ablation Depth on the Endothelial Status of Eyes of Myopic Patients Undergoing Transepithelial Photorefractive Keratectomy: A Retrospective Study in Saudi Arabia. Cureus. 2024;16(7). Petrillo F, Pignataro D, Lavano MA, Santella B, Folliero V, Zannella C, et al. Current evidence on the ocular surface microbiota and related diseases. Microorganisms. 2020;8(7):1033. Rahmani S, Beyramvand AF, Ali SH, Baghban AA, Kangari H. Investigation of visual acuity and residual refractive error after cataract surgery in patients with senile cataract by phacoemulsification. 2020. Additional Declarations No competing interests reported. Supplementary Files FullData.xlsx Cite Share Download PDF Status: Published Journal Publication published 30 Sep, 2025 Read the published version in BMC Ophthalmology → Version 1 posted Editorial decision: Revision requested 30 Apr, 2025 Reviews received at journal 29 Apr, 2025 Reviewers agreed at journal 20 Apr, 2025 Reviews received at journal 08 Apr, 2025 Reviewers agreed at journal 08 Apr, 2025 Reviewers invited by journal 02 Apr, 2025 Submission checks completed at journal 28 Mar, 2025 First submitted to journal 25 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5477082","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":437700152,"identity":"5c829de3-90f5-42bd-9480-fcd33428ff01","order_by":0,"name":"Hassan A. Aljaberi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABI0lEQVRIiWNgGAWjYBACAwQjgfEwAwMzDz9c7gAY4dXCANYi2UCqFgaDA0hasAFz9uOPP/zcwSBvzp5jcLigxlrG+Eby0c08fxjk+G4kMB54g6nFsifHTLL3DIPhzp43BodnHEvnMbuRlnabt43BWPJGAsPBOVgcdiCHjQGogHHDDaAtPGyHgVpyzG7zNjAkbgBqOcyDRcv5548//m1jsIdo+XeYx3gGUAvQYfU4tdxIMJAG2pII1sLbdpjHQAKkhY0hwQCnljdm0rJtEsk7e54VHObtS+eROPMs7ebcNgnDmWceNmD1y/n0xx/fttnYbmdP3viY55u1PX978rEbb/7YyPMdTz78AUuIQYEEVhHGBgYsDiMEyNAyCkbBKBgFww4AAE98cfmOu1JKAAAAAElFTkSuQmCC","orcid":"","institution":"College of Health and Medical Techniques, Al-Mustaqbal University, 51001, Hillah","correspondingAuthor":true,"prefix":"","firstName":"Hassan","middleName":"A.","lastName":"Aljaberi","suffix":""},{"id":437700153,"identity":"6cc37c75-aa9b-4b63-b2b5-a4f3f12e3da7","order_by":1,"name":"Saeed Rahmani","email":"","orcid":"","institution":"Faculty of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran","correspondingAuthor":false,"prefix":"","firstName":"Saeed","middleName":"","lastName":"Rahmani","suffix":""},{"id":437700154,"identity":"73e18200-3ba9-40ef-a7c3-2a8d9ec1724e","order_by":2,"name":"Amel Muhson Naji","email":"","orcid":"","institution":"Dijlah University College, Al-Masafi Street, Al-Dora, Baghdad, 00964","correspondingAuthor":false,"prefix":"","firstName":"Amel","middleName":"Muhson","lastName":"Naji","suffix":""}],"badges":[],"createdAt":"2024-11-18 14:54:02","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5477082/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5477082/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12886-025-04162-0","type":"published","date":"2025-09-30T15:58:17+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79906193,"identity":"c1942c47-5683-4749-9918-336e13655c6a","added_by":"auto","created_at":"2025-04-04 11:04:11","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":32388,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of participants' eyes by age group and gender\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/57a3b56adc48d7fd5bc68836.png"},{"id":79905505,"identity":"6aef009b-a606-41c8-8a5d-38796121088d","added_by":"auto","created_at":"2025-04-04 10:56:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":341673,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot showing a correlation between axial length and corneal radius.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/670e7eb10d853bfd2342a548.png"},{"id":79906187,"identity":"d4aeef5b-0ca1-4e4c-a88f-be987f9b9878","added_by":"auto","created_at":"2025-04-04 11:04:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":190379,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot showing a correlation between axial length and central corneal thickness.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/4de526e28dc76e6b0be1c565.png"},{"id":79906200,"identity":"9b252b87-d13f-46ca-8fdb-2ab9bc186b1c","added_by":"auto","created_at":"2025-04-04 11:04:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":305223,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot showing a correlation between corneal radius and central corneal thickness.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/24cb6562abf10c0bcea1203f.png"},{"id":79904468,"identity":"03274476-1eb4-4512-b962-872c9e0b2037","added_by":"auto","created_at":"2025-04-04 10:48:09","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":176514,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot showing a correlation between SE and central corneal thickness.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/898109cc033ea422b3baaab0.png"},{"id":79907563,"identity":"aec78bb2-c3c4-4b24-bcaf-26523b813697","added_by":"auto","created_at":"2025-04-04 11:12:11","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":334454,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot showing a SE and corneal radius (CR) correlation.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/175d000feba30abc87c2d2c9.png"},{"id":79904531,"identity":"cf0b5800-4601-4ac1-b0e9-cf9141264194","added_by":"auto","created_at":"2025-04-04 10:48:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":27118,"visible":true,"origin":"","legend":"\u003cp\u003eBoxplot of axial length by gender\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/1d551596c31e77b920cbc3fa.png"},{"id":79904496,"identity":"eba0ae0e-0fff-4c6a-9684-458975a9fd65","added_by":"auto","created_at":"2025-04-04 10:48:11","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":47476,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of patients' eyes by type of refractive error.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/22119ec352515df388559068.png"},{"id":79905535,"identity":"2632d418-45af-4e57-8fc6-f54bc36601a2","added_by":"auto","created_at":"2025-04-04 10:56:12","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":43499,"visible":true,"origin":"","legend":"\u003cp\u003eBoxplot of axial length (AL) by spherical equivalent (SE).\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/ad18ce9bb6c49081a8905c0f.png"},{"id":79905512,"identity":"98765d2e-27cd-4623-a52b-597aa2aff363","added_by":"auto","created_at":"2025-04-04 10:56:10","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":37853,"visible":true,"origin":"","legend":"\u003cp\u003eBoxplot of Axial Length across Refractive Error Groups\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/dba397ef7247c1a50c9238ea.png"},{"id":79905511,"identity":"926a9112-5eab-4796-931d-d156ba3305b0","added_by":"auto","created_at":"2025-04-04 10:56:10","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":40702,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot central corneal thickness across Refractive Error Groups\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/0acc3c6e2f8513f4f0f162ab.png"},{"id":79907562,"identity":"1b02c935-cf56-4c4d-808b-ac8734e62bb0","added_by":"auto","created_at":"2025-04-04 11:12:11","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":39033,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot of corneal radius across refractive error groups\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/f739d26ca191b8213f35fff7.png"},{"id":79904470,"identity":"c5a00362-72b8-4229-a854-3799b97c633e","added_by":"auto","created_at":"2025-04-04 10:48:10","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":99009,"visible":true,"origin":"","legend":"\u003cp\u003eP-value comparison between males and females by age groups.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/98613f9d55fc97b3bdaed24e.png"},{"id":79908440,"identity":"e80e3ef4-a2ef-4b6c-9fd6-ec4044662f5c","added_by":"auto","created_at":"2025-04-04 11:20:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2160728,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/69ff90a4-5dca-445e-b70a-6b6d753b8aaf.pdf"},{"id":79905527,"identity":"3e4450a6-4808-468d-abaf-4d9e1aa1586e","added_by":"auto","created_at":"2025-04-04 10:56:11","extension":"xlsx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":181008,"visible":true,"origin":"","legend":"","description":"","filename":"FullData.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5477082/v1/40f1b5a2f7ff00db6a6da974.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBiometric ocular measures, including axial length (AL), corneal radius (CR), and central corneal thickness (CCT), are essential in assessing the refractive state of the eye. Variations in these biometric characteristics are strongly associated with an increase of refractive errors, including myopia, hyperopia, and astigmatism. For instance, an elongated axial length is often correlated with myopia, while a shorter axial length typically results in hyperopia. The amount of refractive error is affected by the cornea's shape and thickness, which in turn affect the retina's ability to focus light. Based on the prevalence and influence on quality of life, research shows that refractive errors continue to be a major public health concern [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. About 157\u0026nbsp;million people across the globe have difficulties seeing because their refractive defects have not been corrected, according to the World Health Organization (WHO) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. When the eye is unable to properly focus light onto the retina, an inaccurate image is formed, leading to refractive errors [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. A number of abnormalities in ocular biometric parameters, including axial length, corneal curvature, central corneal thickness, and the lens, contribute to refractive errors such myopia, hyperopia, and astigmatism [\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Research shows that understanding these eye biometric variables is crucial for developing plans to control and avoid refractive errors [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOcular biometrics and refractive errors were reported in several studies focusing on Iran. In Tehran, Hashemi et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] found that the mean axial length was significantly longer in myopic eyes than in emmetropic and hyperopic eyes. The overall prevalence of myopia was estimated to be 21.8% among participants aged 40 to 64, which is an emerging public health problem. Fu et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported a myopia prevalence of 4.4% among school-going children; this suggests that geographical and lifestyle factors influence refractive error development.\u003c/p\u003e \u003cp\u003eThis has also been furthered by research into the aspects of ocular biometrics related to refractive errors contributed by Mukazhanova et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] documented myopia to be at 25.3% among university students in Kazakhstan, and Wang et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] at 53.7% among high school students in eastern China. The present findings support previous literature regarding the rising prevalence of myopia in the urban and educated populations, as documented by Philip et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] in the analysis of refractive errors in South Indian adults.\u003c/p\u003e \u003cp\u003eThe better ophthalmic health infrastructure in Saudi Arabia has enabled it to study myopia in greater detail [\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Wang et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] estimated the prevalence of myopia and reported that 34.5% of high school students in eastern China, are myopic did not wear glasses. Indeed, a significant association of higher axial length was noted, associated with myopic refractive error. Some studies identified urbanization and socioeconomic factors in the variation of the prevalence of refractive errors, observing a higher prevalence in places where near-work activities were more usual in urban settings [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA comparison of these studies indicates that genetic predisposition factors occur in refractive errors, but environmental and lifestyle factors are essential contributors in the Middle East [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The prevalence of myopia indeed differs in neighboring countries, being higher than its rates in other more urbanized regions and where the engagement in near-work activities is higher [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Myopic individuals' mean axial length is invariably more extended than emmetropic and hyperopic individuals; thus, it is an essential biometric marker [\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhile numerous studies have explored the relationship between biometric parameters and refractive errors globally, research in the Middle East and particularly Iraq remains limited [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. This gap in knowledge is significant given the unique sociocultural, genetic, and environmental factors in Iraq that may influence the development of refractive errors. To address the rising public health concern of uncorrected refractive defects, shape future therapies, and contribute significant data to the worldwide ophthalmic knowledge base, it is crucial to understand these linkages. Prior research in nearby nations like Saudi Arabia and Iran found strong links between axial length (AL) and refractive errors; variations in these relationships were explained by environmental, genetic, and socioeconomic variables. [\u003cspan additionalcitationids=\"CR31\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo address this gap, researchers at Iraq's Al-Mustaqbal University examined the relationship between biometric ocular characteristics and refractive errors in college students and staff. Lifestyle factors, such as restricted outside exposure and prolonged near-work activities, have been associated with the development of myopia, putting university students at a higher risk for refractive errors.\u003c/p\u003e \u003cp\u003eThis study will help provide insight on the biometric factors that lead to refractive errors in the Iraqi population by addressing a data gap in the region. Also, it will serve as the groundwork for public health initiatives in the future that aim to control and prevent refractive defects in young people, a group that is becoming more vulnerable as a result of contemporary lifestyle choices.\u003c/p\u003e"},{"header":"2. Subjects and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Subjects\u003c/h2\u003e \u003cp\u003eThis study was carried out at Al-Mustaqbal University in Iraq during the 2023\u0026ndash;2024 academic year. A total of 1,841 subjects were enlisted, encompassing 3,682 eyes, with ages ranging from 18 to 33 years. The majority of participants were female (57.77%, n\u0026thinsp;=\u0026thinsp;2127), whereas males comprised 42.23% (n\u0026thinsp;=\u0026thinsp;1555). The overall mean age was 22.21\u0026thinsp;\u0026plusmn;\u0026thinsp;3.41 years. The sample size (n\u0026thinsp;=\u0026thinsp;3682 eyes) was determined based on an a priori statistical power analysis to detect small to moderate effect sizes (Cohen\u0026rsquo;s d\u0026thinsp;=\u0026thinsp;0.2\u0026ndash;0.5) with 80% power and a 95% confidence level. The relatively large sample size was intended to enhance the robustness and reliability of the results. While the sample was drawn from a university population, this group represents a critical demographic where refractive errors are increasingly prevalent due to environmental and lifestyle factors. Nonetheless, we acknowledge that the sample may not fully capture the diversity of the broader Iraqi young adult population. This limitation is noted in the discussion, and future research should include broader geographic and socioeconomic representation to enhance generalizability.\u003c/p\u003e \u003cp\u003eParticipants were selected based on clear inclusion and exclusion criteria. All subjects were required to be students or employees at Al-Mustaqbal University at the time of data collection. Participants with a history of ocular surgery, systemic diseases (e.g., diabetes), ocular trauma, or unrelated eye conditions were excluded. Only individuals with stable ocular health were included to avoid factors that could affect refractive outcomes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the distribution of participants' eyes by age group and gender. Younger individuals, particularly in the 18\u0026ndash;21 and 22\u0026ndash;25 age groups, were more represented, which is reflective of typical university demographics. This trend aligns with typical university demographics, where female participation may be higher in certain disciplines. Separating participants by gender and age helps reduce bias and facilitates more accurate comparisons of biometric measurements across different groups.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Examinations and Assessments\u003c/h2\u003e \u003cp\u003eDetailed ophthalmologic examinations were conducted on all 1841 individuals, resulting in a total of 3682 eyes examined. Refraction was assessed using automated refraction followed by subjective refinement to determine the spherical equivalent refractive error for each eye. Axial length (AL) was measured using a non-contact IOL Master, which provides high-precision ocular biometry. Corneal curvature was measured using the Topcon KR-800 Auto Kerato-Refractometer. Central corneal thickness (CCT) was measured using an ultrasonic pachymeter, which was specifically selected due to its clinical accuracy, portability, and proven reliability across diverse patient groups. While the IOL Master does offer a corneal thickness measurement function, in our setting it was not available with the upgraded CCT module. Furthermore, the ultrasonic pachymeter has been validated in multiple studies for precise corneal thickness assessment and remains a gold-standard method in many clinical contexts. The devices used were the latest models available in our university laboratories and were regularly calibrated and maintained by certified optometrists and ophthalmologists to ensure measurement precision. This method allowed us to capture accurate biometric data suitable for robust statistical analysis.\u003c/p\u003e \u003cp\u003eFurthermore, anthropometric measurements, encompassing ocular biometrics, were collected, succeeded by additional assessments to investigate the relationships between ocular dimensions and other ophthalmological parameters pertinent to refractive errors. This thorough methodology offered a detailed perspective on the ocular health status of the study population.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Definitions\u003c/h2\u003e \u003cp\u003eRefractive error (RE) is categorized according to the spherical equivalent (SE), ascertained by aggregating the spherical value with half of the cylindrical value. Myopia or nearsightedness is defined by a spherical equivalent (SE) of \u0026ge; -0.50 diopters (D). Mild to moderate myopia is defined as ranging from \u0026minus;\u0026thinsp;0.50D to -6.00D, but severe myopia is characterized by a spherical equivalent above \u0026minus;\u0026thinsp;6.00D. Hyperopia, or farsightedness, is defined by a spherical equivalent (SE) of \u0026ge;\u0026thinsp;+\u0026thinsp;0.50 diopters (D). Astigmatism is defined as a cylindrical refractive error of \u0026ge;\u0026thinsp;0.50 diopters, irrespective of the spherical equivalent. These classifications align with recommendations from prominent ophthalmologic conferences and generally recognized research.\u003c/p\u003e \u003cp\u003eAxial length (AL) is the measurement from the corneal surface to the retina, significantly influencing refractive errors. An elongated axial length (AL) is linked to myopia, whereas a shortened AL is connected with hyperopia. The corneal radius (CR) denotes the curvature of the cornea; anomalies in CR are associated with astigmatism and other refractive disorders. center corneal thickness (CCT) quantifies the thickness of the cornea's center region and is crucial for evaluating intraocular pressure and refractive disorders, including glaucoma.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Data Analysis\u003c/h2\u003e \u003cp\u003eSPSS version 26.0 (SPSS Corp., Chicago, USA) was used to evaluate the data. The spherical equivalent (SE) and axial length (AL) of each eye were measured objectively on all of the patients. The Kolmogorov-Smirnov test was used to see if the distributions of SE, AL, corneal, central corneal thickness (CCT), and radius (CR) were normal in both men and women. A significance level of p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 meant that the distributions were normal. We used Pearson correlation coefficients to look at the connections between AL, CCT, CR, and SE for both male and female subjects. A p value of less than 0.001 was used to determine statistical significance. To account for differences between people, the study used measurements from both the right and left eyes. Paired samples t-tests with a significance level of p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were used to compare SE and AL by gender.\u003c/p\u003e \u003cp\u003eOne-way analysis of variance (ANOVA) was used to compare changes in axial length between groups of refractive error. The study focused on mild myopia, hyperopia, and astigmatism. We used the least significant difference (LSD) test to find significant group differences in post hoc studies. For inter-group comparisons, a p-value of less than 0.001 was considered statistically significant. The data are shown as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;the standard deviation, along with 95% confidence ranges. Because there were a lot more women than men who participated, most of the studies were done with subgroups of people of the same gender. Box plots and tables show descriptive terms like AL, CR, CCT, and SE so that they can be compared across different types of refractive error.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003e\u003cem\u003e3.1.\u0026nbsp;Biometric Parameters and Refractive Error Distribution\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe mean axial length (AL) for all individuals was 24.45 \u0026plusmn; 1.10 mm, the mean corneal radius (CR) was 7.37 \u0026plusmn; 0.77 mm, and the mean central corneal thickness (CCT) was 555.83 \u0026plusmn; 50.83 \u0026micro;m. \u0026nbsp;Table 1 delineates the average ocular biometric data categorized by type of refractive error. \u0026nbsp;Deviations in corneal curvature in myopic and hyperopic patients presumably arise from a confluence of genetic, environmental, developmental, and measurement-related factors. \u0026nbsp;These variances are crucial for comprehending the complete intricacy of refractive defects and their clinical therapy. \u0026nbsp;The clinical interpretation of refractive error data is constrained without a thorough examination of the interaction between corneal curvature and axial length in these patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eMean ocular biometric measurements stratified by refractive error type, including AL, CR, and CCT.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"558\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 106px;\"\u003e\n \u003cp\u003eRefractive Error\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eAL Mean \u0026plusmn; SD (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eCR Mean \u0026plusmn; SD (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eCCT Mean \u0026plusmn; SD (\u0026micro;m)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 106px;\"\u003e\n \u003cp\u003eMyopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e1871\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e25.11 \u0026plusmn; 0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e6.86 \u0026plusmn; 0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e565.62 \u0026plusmn; 12.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 106px;\"\u003e\n \u003cp\u003eHyperopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e626\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e22.71 \u0026plusmn; 0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e8.53 \u0026plusmn; 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e495.42 \u0026plusmn; 18.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 106px;\"\u003e\n \u003cp\u003eAstigmatism\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e1185\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e24.31 \u0026plusmn; 0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e7.54 \u0026plusmn; 0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e530.93 \u0026nbsp; \u0026nbsp;39.94\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003e3.2.\u0026nbsp;Correlation Analyses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTo examine the correlations between various biometric parameters, scatter plots have been constructed to understand their interaction with refractive errors. Figure 2 illustrates a notable negative correlation between axial length (AL) and corneal radius (CR), emphasizing the compensatory link between these parameters in sustaining refractive equilibrium. The results indicate that myopia is influenced not only by axial length elongation but also by corneal steepening (reduced curvature radius), which increases refractive power. Likewise, hyperopia results from a conjunction of reduced axial length and a flatter cornea (elevated curvature radius). These studies highlight the interconnected relationship between axial length (AL) and corneal radius (CR) in the progression of refractive error. The moderate correlation strength indicates that additional factors, such as lens thickness and anterior chamber depth, contribute to refractive outcomes.\u003c/p\u003e\n\u003cp\u003eFigure 3 depicts the correlation between axial length (AL) and central corneal thickness (CCT), showing an extremely strong positive association (r = 0.88, p \u0026lt; 0.001). \u0026nbsp;As AL rises, CCT rises proportionally.\u003c/p\u003e\n\u003cp\u003eFigure 4 illustrates the relationship between central corneal thickness and corneal radius, revealing a moderate negative association (r = -0.577, p \u0026lt; 0.001). \u0026nbsp;As CCT declines, CR rises.\u003c/p\u003e\n\u003cp\u003eFigure 5 illustrates the association between spherical equivalent and central corneal thickness, demonstrating an extremely strong negative correlation (r = -0.883, p \u0026lt; 0.001). \u0026nbsp;As SE declines, CCT escalates.\u003c/p\u003e\n\u003cp\u003eFigure 6 illustrates a moderate positive correlation between corneal curvature radius (CR) and spherical equivalent (SE), highlighting the critical role of corneal curvature in shaping refractive power.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.3.\u0026nbsp;Gender Differences in Biometric Parameters\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFigure 7 shows the distribution of ALs by sex, revealing that females tended to have longer axial lengths (25.35 \u0026plusmn; 0.50 mm) than males did (24.95 \u0026plusmn; 0.61 mm), which was a statistically significant difference (p \u0026lt; 0.001).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.4.\u0026nbsp;Prevalence of Refraction Errors and Ocular Biometric Parameters by Gender\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFigure 8 illustrates the prevalence of refraction errors categorized by sex. Myopia and astigmatism were more prevalent in females, while hyperopia showed a similar distribution across sexes.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.5.\u0026nbsp;Ocular Biometric Differences by Refractive Error Group\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFigure 9 shows the eyes with shorter ALs (\u0026lt;23 mm) were predominantly hyperopic, while longer ALs (\u0026gt;25 mm) were associated with myopia.\u003c/p\u003e\n\u003cp\u003eFigure 10 shows the myopic eyes had the longest ALs (24\u0026ndash;26 mm), while hyperopic eyes had the shortest (\u0026lt;23 mm).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.6.\u0026nbsp;Central Corneal Thickness and Corneal Radius Across Refractive Error Groups\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFigure 11 shows the myopic eyes had the thickest CCT (550\u0026ndash;600 \u0026micro;m), while hyperopic eyes had the thinnest (\u0026lt;500 \u0026micro;m).\u003c/p\u003e\n\u003cp\u003eFigure 12 shows the myopic eyes had the steepest corneas (6.5\u0026ndash;7.5 mm CR), and hyperopic eyes had the flattest (8.0\u0026ndash;9.0 mm CR).\u003c/p\u003e\n\u003cp\u003eFigure 13 shows the p-values for axial length, corneal radius, and central corneal thickness across different age groups. The p-values for axial length are particularly low in the 18\u0026ndash;21 age group, indicating significant variation in axial length with age. For the corneal radius, the p-values remain below the significance threshold but increase with age. The statistical significance of central corneal thickness decreases with age but remains relevant.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.7.\u0026nbsp;Analysis of biometric ocular parameters across refractive error groups and gender differences\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eOcular biometric characteristics axial length, corneal radius, and central corneal thickness are compared across myopic, hyperopic, and astigmatic refractive error groups. A gender-based breakdown is also provided to analyze differences between male and female participants within each refractive error group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eOne-way ANOVA for biometric ocular parameters among refractive error groups\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eF-statistic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAxial Length\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eF(2, 3697) = 2967\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep \u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCorneal Curvature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eF(2, 3697) = 2936\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep \u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCentral Corneal Thickness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eF(2, 3697) = 1944\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep \u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 2 presents the findings of the one-way analysis of variance (ANOVA) for biometric ocular parameters across refractive error categories (p \u0026lt; 0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u0026nbsp;\u003c/strong\u003eMean axial length by refractive error and gender\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003eRefractive Error\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003eMyopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 48px;\"\u003e\n \u003cp\u003e739\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003e25.04 \u0026plusmn; 0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.01 - 25.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e1132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.15 \u0026plusmn; 0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.13 - 25.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003eHyperopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 48px;\"\u003e\n \u003cp\u003e317\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003e22.60 \u0026plusmn; 0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.53 - 22.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e309\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.82 \u0026plusmn; 0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.74 - 22.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003eAstigmatism\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 48px;\"\u003e\n \u003cp\u003e499\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003e24.17 \u0026plusmn; 0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.09 - 24.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e686\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.42 \u0026plusmn; 0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.35 - 24.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 3 compares axial length (AL) between males and females within each refractive error group. Females consistently exhibit significantly longer ALs than males across all groups (p \u0026lt; 0.0001). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4\u0026nbsp;\u003c/strong\u003ePairwise comparisons of axial length by refractive error groups\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGroup 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGroup 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMean Difference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMyopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAstigmatism\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.794\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.736 - 0.852\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMyopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eHyperopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.399\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.345 - 2.454\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAstigmatism\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eHyperopia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.606\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.531 - 1.681\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 4 presents axial length comparisons within each refractive error group and overall, using the LSD method. Significant differences were observed: myopic participants had a greater axial length than astigmatic participants (mean difference: 0.794 mm, p \u0026lt; 0.0001) and hyperopic participants (mean difference: 2.399 mm, p \u0026lt; 0.0001). Astigmatic eyes also exhibited a longer axial length than hyperopic eyes (mean difference: 1.606 mm, p \u0026lt; 0.0001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5\u0026nbsp;\u003c/strong\u003eMean axial length (AL) by spherical equivalent (SE) range and sex\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"633\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"bottom\" style=\"width: 47px;\"\u003e\n \u003cp\u003eGroup\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"bottom\" style=\"width: 95px;\"\u003e\n \u003cp\u003eSE\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 217px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 94px;\"\u003e\n \u003cp\u003eMean AL \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003eMean AL \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 66px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.50 to -2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e519\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e24.64 \u0026plusmn; 0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.62 - 24.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003e769\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.82 \u0026plusmn; 0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e24.81 - 24.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-2.25 to -4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e456\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e25.28 \u0026plusmn; 0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.26 - 25.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003e666\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.44 \u0026plusmn; 0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.43 - 25.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-4.25 to -6.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e25.95 \u0026plusmn; 0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e25.89 - 26.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e26.13 \u0026plusmn; 0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e26.06 - 26.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e= 0.0003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e+0.50 to +2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e280\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e23.31 \u0026plusmn; 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e23.26 - 23.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003e350\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e23.57 \u0026plusmn; 0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e23.52 - 23.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e+2.25 to +4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e247\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e22.32 \u0026plusmn; 0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.26 - 22.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 38px;\"\u003e\n \u003cp\u003e270\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.64 \u0026plusmn; 0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 85px;\"\u003e\n \u003cp\u003e22.58 - 22.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt; 0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 5 summarizes axial length (AL) by sex and spherical equivalent (SE) range, showing significant sex differences across all SE groups. Females consistently exhibit longer AL than males, including in the SE range -0.50 to -2.00 (females: 24.82 \u0026plusmn; 0.22 mm; males: 24.64 \u0026plusmn; 0.25 mm, p \u0026lt; 0.0001), -2.25 to -4.00 (females: 25.44 \u0026plusmn; 0.23 mm; males: 25.28 \u0026plusmn; 0.20 mm, p \u0026lt; 0.0001), and -4.25 to -6.00 (females: 26.13 \u0026plusmn; 0.29 mm; males: 25.95 \u0026plusmn; 0.25 mm, p = 0.0003).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study clarifies the relationship between biometric ocular characteristics and refractive errors in participants from Al-Mustaqbal University in Iraq. Fan et al. [33] identified a comparable tendency, noting a substantial association between axial length (AL) and refractive error in university students of Chinese descent, with myopes demonstrating greater AL than hyperopes or emmetropes. These results contribute to the existing literature on ocular biometrics and refractive errors, especially within Middle Eastern populations.\u003c/p\u003e\n\u003cp\u003eThe gender differences observed in our study have implications for clinical practice and public health policies. Our results indicate that females tend to develop certain types of refractive errors, such as myopia and astigmatism, at a younger age than males. This aligns with Zeried et al.\u0026apos;s findings [19] on gender-sensitive attitudes towards refractive correction among Saudi students. Recognizing these gender-specific dynamics is crucial for developing effective therapies and prevention strategies, particularly for young women who are at a higher risk of developing severe myopia.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCompared with male participants, females generally had longer axial lengths across various refractive error and SE categories, a trend that differs from that of Fan et al. [33], who reported that Chinese male students had longer ALs. Our findings suggest that genetic and environmental factors may play a significant role in determining axial length (AL) in females, particularly in cases of high myopia. Females consistently exhibited longer ALs than males across various refractive error groups and spherical equivalent (SE) ranges, as shown in the study. This trend was especially evident in high myopia, such as in the -4.25 to -6.00 SE range, where females had significantly longer ALs (26.13 \u0026plusmn; 0.29 mm) compared to males (25.95 \u0026plusmn; 0.25 mm, p = 0.0003). These differences may be influenced by genetic and hormonal factors, as well as lifestyle elements such as increased near-work activities and reduced outdoor exposure, which are more common among females in specific demographic groups. Together, these findings emphasize the pivotal role of genetic and environmental factors in shaping AL, particularly in females with high myopia.\u003c/p\u003e\n\u003cp\u003eThe study also revealed a strong correlation between the AL and refractive error. Longer ALs are associated with myopia, reinforcing the well-established concept that eye elongation exacerbates myopia, with a focus on light in front of the retina. Conversely, hyperopic eyes had shorter ALs, causing light to focus behind the retina, resulting in farsightedness. These observations support previous research, such as the Tehran Geriatric Eye Study by Hashemi et al. [11], and are consistent with findings from Bikbov et al. [6], who explored similar patterns in children and adolescents.\u003c/p\u003e\n\u003cp\u003eCentral corneal thickness (CCT) has been shown to correlate with refractive status, particularly in myopic individuals. The study confirms that myopic eyes tend to have thicker corneas compared to hyperopic eyes. This may serve as a compensatory mechanism to maintain structural integrity as axial length (AL) increases in myopic eyes. Increased AL can create additional stress on the ocular structures, and a thicker cornea may help prevent distortion and deformation under higher intraocular pressure, which is more commonly observed in myopia.\u003c/p\u003e\n\u003cp\u003eHowever, not all studies align with this finding. For instance, Almazrou et al. [34], reported no significant differences in CCT between myopic and non-myopic individuals, suggesting variability in CCT\u0026rsquo;s relationship with myopia. This discrepancy highlights the need for further research to better understand how CCT interacts with different degrees of myopia and other ocular parameters. These CCT differences have important implications for patient management, particularly in refractive surgeries, as noted by Khoramnia et al. [7].\u003c/p\u003e\n\u003cp\u003eWhile CCT is typically thicker in myopic individuals, it does not appear to change significantly with minor shifts in refractive status. Instead, its relationship with refractive errors may reflect broader compensatory adaptations in highly myopic eyes. It remains unclear if CCT itself contributes directly to refractive error progression or is merely a consequence of structural adjustments related to AL elongation. This area warrants further investigation, particularly in longitudinal studies that can track changes in CCT and refractive error development over time.\u003c/p\u003e\n\u003cp\u003eCCT tends to decrease with age, a pattern well-documented in various populations. This thinning is believed to result from biomechanical and biochemical changes in the corneal stroma, such as a reduction in collagen density and hydration levels. Older adults generally exhibit thinner corneas, which could have implications for refractive error stability and intraocular pressure measurements, as thinner corneas may lead to underestimation of intraocular pressure. This age-related thinning may also partially explain differences in refractive error patterns between younger and older populations, as thinner corneas may contribute to changes in refractive stability.\u003c/p\u003e\n\u003cp\u003eA moderate negative correlation was observed between central corneal thickness (CCT) and corneal radius (CR) (r = -0.577, p \u0026lt; 0.001), indicating that thinner corneas are associated with flatter curvature. This relationship underscores the biomechanical interplay between corneal thickness and curvature, particularly in myopic eyes. Thinner corneas may contribute to reduced structural rigidity, leading to compensatory flattening of the cornea. These findings are clinically significant for assessing refractive error progression, surgical planning, and identifying early signs of corneal instability.\u003c/p\u003e\n\u003cp\u003eThere are several limitations to this study. Since it focused on healthy university students, the findings may not be generalizable to other populations, such as older adults or children, who may exhibit different refractive error patterns. Additionally, the cross-sectional nature of the data makes it challenging to assess changes in refractive errors over time. Future longitudinal research should explore these trends further and investigate how genetic and environmental factors contribute to sex differences in AL. More research is needed to understand the role of CCT in postsurgical patients, especially those who have undergone corneal refractive surgery.\u003c/p\u003e\n\u003cp\u003eChanges in CCT provide critical information when performing refractive surgeries such as LASIK or photorefractive keratectomy. Corneal thickness should be assessed with refractive error prior to planning surgical treatments, particularly for patients who have major myopia or hyperopia. This matches Alrashidi\u0026apos;s study [35] about the impact of elimination depth on endothelial health in Saudi patients undergoing photorefractive keratectomy. Our findings could help specialists in adjusting their techniques based on patient features, potentially reducing adverse surgical outcomes.\u003c/p\u003e\n\u003cp\u003eThe results of this study require more investigation, particularly concerning the lasting influence of genetic and environmental factors on gender differences in AL. The hypothesized importance of the ocular surface bacteria in the emergence of refractive error necessitates additional research. [36]. Recent studies suggest that an imbalance in the ocular surface microbiome may trigger inflammatory responses and biomechanical degradation of the cornea, particularly influencing parameters such as central corneal thickness (CCT) and corneal curvature (CR). These abnormalities may exacerbate myopia progression or result in conditions like as keratoconus, which is marked by anomalies in corneal curvature. Given the increasing prevalence of myopia and its association with environmental and lifestyle factors, more investigation into the ocular microbiome may provide valuable insights into the pathogenesis of refractive defects and uncover novel therapeutic or preventive strategies. Moreover, further research is required to examine the relationship between CCT and refractive outcomes in post-surgical patients, since this may significantly impact long-term treatment strategies [37].\u003c/p\u003e\n\u003cp\u003eIn conclusion, our research underscores the importance of biometric ocular factors such as axial length, corneal curvature, and central corneal thickness in evaluating refractive status. \u0026nbsp;These findings corroborate and enhance prior research carried out in nearby regions and globally. Our findings suggest that female students may be more susceptible than male students to severe refractive errors, particularly myopia, underscoring the necessity for gender-sensitive strategies for addressing this problem. As urbanization and lifestyle changes continue to impact refractive error prevalence in the Middle East and worldwide, our findings contribute valuable knowledge that can inform public health and clinical strategies for addressing this significant health concern. This study\u0026rsquo;s insights have direct applications in patient management and public health, as uncorrected refractive errors remain one of the leading causes of visual impairment globally.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors sincerely thank the Deanship of the College of Health and Medical Techniques at Al-Mustaqbal University for their valuable assistance in data collection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHassan A. Aljaberi and Saeed Rahmani conceived and supervised the experiment and also conducted the study. Amal Mohsen Naji collected and analyzed the data. Hassan A. Aljaberi drafted the manuscript, while Saeed Rahmani revised it. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAccessibility of resources and data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data supporting the findings of this investigation are accessible in the supplemental material of this publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;Approval of ethics and consent for participation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures were conducted in compliance with the ethical norms established by the institutional and national research committees, in addition to the Declaration of Helsinki. \u0026nbsp;The Research Ethics Committee of the Faculty of Health and Medical Techniques of Al-Mustaqbal University accepted this study on 23/09/2023 (reference number 23092023). \u0026nbsp; All study participants provided informed consent to participate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthorization for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors assert that they possess no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003e Optics Techniques Department, College of Health and Medical Techniques, Al-Mustaqbal University, 51001, Hillah, Iraq\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e2\u003c/sup\u003e Department of Optometry, Faculty of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e3\u003c/sup\u003e Department of Optics Techniques, Dijlah University College, Al-Masafi Street, Al-Dora, Baghdad, 00964, Iraq\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe date that supports the findings of this study are available in the supplementary material of this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHashemi A, Khabazkhoob M, Hashemi H. High prevalence of refractive errors in an elderly population; a public health issue. BMC Ophthalmol. 2023;23(1):38.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMagakwe TS, Hansraj R, Xulu-Kasaba ZN. The impact of uncorrected refractive error and visual impairment on the quality of life amongst school-going children in Sekhukhune district (Limpopo), South Africa. Afr Vis Eye Health. 2022;81(1):7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePirindhavellie G-P, Yong AC, Mashige KP, Naidoo KS, Chan VF. The impact of spectacle correction on the well-being of children with vision impairment due to uncorrected refractive error: a systematic review. BMC Public Health. 2023;23(1):1575.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStudy VLEGotGBoD. Global estimates on the number of people blind or visually impaired by Uncorrected Refractive Error: a meta-analysis from 2000 to 2020. Eye. 2024;38(11):2083.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNser HY, Al-Sharify NT, Ahmed SM, Weng LY, See OH, Al-Sharify ZT, et al. editors. Review study of refraction error measurement methods of human cornea. AIP Conference Proceedings; 2023: AIP Publishing.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBikbov MM, Kazakbaeva GM, Fakhretdinova AA, Tuliakova AM, Iakupova EM, Panda-Jonas S, et al. Associations between axial length, corneal refractive power and lens thickness in children and adolescents: The Ural Children Eye Study. Acta Ophthalmol. 2024;102(1):e94\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhoramnia R, Auffarth G, Łabuz G, Pettit G, Suryakumar R. Refractive outcomes after cataract surgery. Diagnostics. 2022;12(2):243.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNg\u0026rsquo;andu A, Krikor E, Mutati GC. Variations in Ocular Biometrics Related to Refractive Errors Among Adult Patients Attending the University Teaching Hospitals-Eye Hospital in Lusaka, Zambia. Anat J Afr. 2022;11(1):2092\u0026ndash;101.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBenzir M, Afroze A, Zahan A, Naznin RA, Khanam A, Sumi SA et al. A study linking axial length, corneal curvature, and Eye Axis with demographic characteristics in the emmetropic eyes of Bangladeshi people. Cureus. 2022;14(10).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFan Y, Wang J, Lei J, Ji J, Xie P, Hu Z. Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia. Graefe's Archive Clin Experimental Ophthalmol. 2024:1\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHashemi H, Heydarian S, Hashemi A, Khabazkhoob M. Axial length and anterior chamber indices in elderly population: Tehran Geriatric Eye Study. Int J Ophthalmol. 2023;16(11):1876.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFu A, Watt K, Junghans M, Delaveris B, Stapleton A. Prevalence of myopia among disadvantaged Australian schoolchildren: A 5-year cross-sectional study. PLoS ONE. 2020;15(8):e0238122.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMukazhanova A, Aldasheva N, Iskakbayeva J, Bakhytbek R, Ualiyeva A, Baigonova K, et al. Prevalence of refractive errors and risk factors for myopia among schoolchildren of Almaty, Kazakhstan: A cross-sectional study. PLoS ONE. 2022;17(6):e0269474.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J, Ying G-s, Fu X, Zhang R, Meng J, Gu F, et al. Prevalence of myopia and vision impairment in school students in Eastern China. BMC Ophthalmol. 2020;20:1\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePhilip K, Sankaridurg P, Naduvilath T, Konda N, Bandamwar K, Kanduri S, et al. Prevalence and patterns of refractive errors in children and young adults in an urban region in south India: The Hyderabad eye study. Ophthalmic Epidemiol. 2023;30(1):27\u0026ndash;37.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl Nahedh T. Current Concepts of Myopia, Etiology, and Recent Treatments in Saudi Arabia. J Health Inf Developing Ctries. 2023;17(01).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlghamdi W, Ovenseri-Ogbomo GO. The prevalence and causes of visual impairment in Dariyah, a rural community in Saudi Arabia. Afr Vis Eye Health. 2021;80(1):5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlrasheed SH, Aldakhil S. Corneal curvature, anterior chamber depth, lens thickness, and vitreous chamber depth: Their intercorrelations with refractive error in Saudi adults. Open Ophthalmol J. 2022;16(1).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZeried FM, Alnehmi DA, Osuagwu UL. A survey on knowledge and attitude of Saudi female students toward refractive correction. Clin Experimental Optometry. 2020;103(2):184\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBiswas S, El Kareh A, Qureshi M, Lee DMX, Sun C-H, Lam JS, et al. The influence of the environment and lifestyle on myopia. J Physiol Anthropol. 2024;43(1):7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHung HD, Chinh DD, Tan PV, Duong NV, Anh NQ, Le NH et al. The Prevalence of myopia and factors associated with it among secondary school children in rural Vietnam. Clin Ophthalmol. 2020:1079\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePhilip K, Paudel P, Vincent J, Marmamula S, Fricke T, Sankaridurg P. Refractive Error and School Eye Health. South-East Asia Eye Health: Systems, Practices, and Challenges. Springer; 2021. pp. 145\u0026ndash;68.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhoshhal F, Hashemi H, Hooshmand E, Saatchi M, Yekta A, Aghamirsalim M, et al. The prevalence of refractive errors in the Middle East: a systematic review and meta-analysis. Int Ophthalmol. 2020;40:1571\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee SS, Mackey DA. Regional Differences in Prevalence of Myopia: Genetic or Environmental Effects? Advances in Vision Research, III: Genetic Eye Research around the Globe. 2021:365\u0026ndash;79.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMorgan IG, Wu P-C, Ostrin LA, Tideman JWL, Yam JC, Lan W, et al. IMI risk factors for myopia. Investig Ophthalmol Vis Sci. 2021;62(5):3\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAssi L, Chamseddine F, Ibrahim P, Sabbagh H, Rosman L, Congdon N, et al. A global assessment of eye health and quality of life: a systematic review of systematic reviews. JAMA Ophthalmol. 2021;139(5):526\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGong X, Wu X-H, Liu A-L, Qian K-W, Li Y-Y, Ma Y-Y, et al. Optic nerve crush modulates refractive development of the C57BL/6 mouse by changing multiple ocular dimensions. Brain Res. 2020;1726:146537.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRozema J, Dankert S, Iribarren R. Emmetropization and nonmyopic eye growth. Surv Ophthalmol. 2023;68(4):759\u0026ndash;83.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRattan SA, Ridha RM, Majeed BQ, Hussien ZZ, Abdullah NA. Awareness and Knowledge About RefractiveSurgery Among Medical Students in Baghdad. Pakistan J Ophthalmol. 2024;40(2).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlexopoulos P, Madu C, Wollstein G, Schuman JS. The development and clinical application of innovative optical ophthalmic imaging techniques. Front Med. 2022;9:891369.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKam KW, Pang CP, Yam JC. Refractive Errors, Myopia, and Presbyopia. Ophthalmic Epidemiol. 2022:87\u0026ndash;112.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLazreg S, Hosny M, Ahad MA, Sinjab MM, Messaoud R, Awwad ST et al. Dry Eye Disease in the Middle East and Northern Africa: a position paper on the current state and unmet needs. Clin Ophthalmol. 2024:679\u0026ndash;98.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFan Q, Wang H, Jiang Z. Axial length and its relationship to refractive error in Chinese university students. Contact Lens Anterior Eye. 2022;45(2):101470.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlmazrou AA, Abualnaja WA, Abualnaja AA, Alkhars AZ, Abualnaja W, Abualnaja A. Central corneal thickness of a Saudi population in relation to age, gender, refractive errors, and corneal curvature. Cureus. 2022;14(10).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlrashidi SH. Effect of Ablation Depth on the Endothelial Status of Eyes of Myopic Patients Undergoing Transepithelial Photorefractive Keratectomy: A Retrospective Study in Saudi Arabia. Cureus. 2024;16(7).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePetrillo F, Pignataro D, Lavano MA, Santella B, Folliero V, Zannella C, et al. Current evidence on the ocular surface microbiota and related diseases. Microorganisms. 2020;8(7):1033.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRahmani S, Beyramvand AF, Ali SH, Baghban AA, Kangari H. Investigation of visual acuity and residual refractive error after cataract surgery in patients with senile cataract by phacoemulsification. 2020.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Refractive errors, Biometric ocular parameters, Students university, Iraq, Cross-sectional study","lastPublishedDoi":"10.21203/rs.3.rs-5477082/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5477082/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo establish the relationship between ocular biometry and refractive errors in young adult Iraqis by analyzing three critical biometric ocular parameters, including axial length (AL), corneal radius (CR), and central corneal thickness (CCT).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA cross-sectional analysis of individuals aged 18-33 years was conducted at Al-Mustaqbal University, Iraq, yielding 1841 participants (3682 eyes). Quantitative data on AL, CR, and CCT were obtained by an Auto Kerato-Refractometer, IOL Master and pachymetry techniques. We used Pearson correlation coefficients to measure the correlation between AL, CR, CCT, and refractive errors (myopia, hyperopia, astigmatism). Gender differences and interactions with these correlations were also examined.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn total, Mean AL was 24.45 ± 1.10 mm; CR was 7.37 ± 0.77 mm; and CCT was 555.83 ± 50.83 µm. Myopic participants had a statistically significantly more significant mean AL of 25.11 ± 0.42 mm than the hyperopic subjects, with a mean AL of 22.71 ± 0.65mm (p \u0026lt; 0.001). Females had slightly longer ALs on average than males in myopic and hyperopic groups of eyes. Myopic individuals also exhibited thicker corneas (mean CCT: 565.62 ± 12.68 µm) compared to hyperopic individuals (mean CCT: 495.42 ± 18.74 µm). Indeed, AL and CCT were significantly related to refractive error, and these findings affirmed AL as a dominant predictor.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis self-gathered outcome resolved alterations AL as a chief contributing factor of refractive mistake; it links with important differentiations partly by sex. The findings of the study help fill existing gaps in the knowledge base and shape future public health interventions aimed at addressing refractive errors among young adults in Iraq.\u003c/p\u003e","manuscriptTitle":"Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-04 10:48:04","doi":"10.21203/rs.3.rs-5477082/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-30T04:05:48+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-29T05:08:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180587170332839588641944006782516036976","date":"2025-04-21T03:48:23+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-09T03:45:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245078655190299241726268793981396234816","date":"2025-04-09T03:35:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-03T03:14:37+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-28T12:39:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Ophthalmology","date":"2025-03-25T09:08:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6eac80cf-29c9-421e-b47d-6a600e75cc72","owner":[],"postedDate":"April 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-06T16:04:59+00:00","versionOfRecord":{"articleIdentity":"rs-5477082","link":"https://doi.org/10.1186/s12886-025-04162-0","journal":{"identity":"bmc-ophthalmology","isVorOnly":false,"title":"BMC Ophthalmology"},"publishedOn":"2025-09-30 15:58:17","publishedOnDateReadable":"September 30th, 2025"},"versionCreatedAt":"2025-04-04 10:48:04","video":"","vorDoi":"10.1186/s12886-025-04162-0","vorDoiUrl":"https://doi.org/10.1186/s12886-025-04162-0","workflowStages":[]},"version":"v1","identity":"rs-5477082","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5477082","identity":"rs-5477082","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}