Long-term longitudinal changes in astigmatism and their effect on refraction development in Chinese clinical school-age children

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Methods The medical records of patients with long-term follow-up data from 2006 to 2018 were retrospectively reviewed. Patients who were 6–10 years old at initial visit and 16 years old at last assessment were selected for analysis. The enrolled patients had a cylinder refraction of 0.75 or greater. Astigmatism was analyzed in clinical notation and vector notation (J0, J45). The related factors of changes in astigmatism and spherical equivalent per year and the interaction between the two were analyzed. Results A total of 3101 patients (median age 9 years at initial visit) were followed up for an average of 7 years (IQR, 6–8 years). Astigmatism increased with age in low astigmats (< 1.50 D, 0.025 D/y) and decreased with age in high astigmats (≥ 3.00 D, -0.048 D/y). The oblique astigmatism (J45, 0.005D/y) increased and with-the-rule (WTR) astigmatism (J0, -0.008D/y) decreased. Higher myopia of the SE at the initial visit was associated with a greater increase in astigmatism magnitude(p < 0.001). A higher magnitude of initial astigmatism was associated with less progression in spherical equivalent(p < 0.001). Conclusion In Chinese clinical school-age children, the longitudinal development of astigmatism from 6–10 to 16 years of age varied with baseline astigmatism. The presence of myopia at baseline was a risk factor for astigmatism progression. However, high astigmatism seems to prevent the progression of myopia. astigmatism spherical equivalent refraction development school-age children Figures Figure 1 Figure 2 Figure 3 Introduction Astigmatism is a highly prevalent refractive error worldwide, frequently coexisting with myopia and hyperopia. There have been population-based reports on the prevalence of astigmatism in children from different ethnic groups, and the prevalence of astigmatism in school-aged children is generally higher in East Asian populations than in other ethnicities.[ 1 – 4 ] Eyelid pressure is most likely to be involved in the development of corneal astigmatism.[ 5 ] Higher lid tension in Asian populations is suggested to be an associated factor leading to a higher prevalence of astigmatism.[ 6 ] Eyelid pressure should change as children age, and the long-term trend of astigmatism in children is not clear. In addition, Gwiazda et al.[ 7 ] analyzed the functional significance of astigmatism in emmetropization and the development of myopia, finding that infantile astigmatism is associated with increased astigmatism and myopia in childhood. Furthermore, the association of high prevalence of astigmatism and increasing myopia in school-age Asian populations raises the question of whether the presence of astigmatism contributes to the development of myopia. [8] A few studies have investigated longitudinal changes in refractive astigmatism and their effects on refractive development in children. Most of these studies are short-term and the majority of them focused on pre-school children. For example, Chan et al.[ 9 ] studied the progression of astigmatism in primary school children and its effect on myopic shift in southern Taiwan over a 1-year period. They found that the astigmatism decreased during the one-year follow-up and was not associated with myopia progression. Fan et al.[ 10 ] studied the progression of astigmatism and its effect on refractive development in preschool children in Hong Kong with a follow-up of 55.7 months. They reported that a significant percentage of children had stable and even increased astigmatism. In addition, children with increased astigmatism had greater myopic progression. The incidences of both astigmatism and myopia are very high in school-age children in southern China.[ 2 , 11 ] However, the developmental interplay between the two has not been explored in this population. In this study, data collected in a large cohort with astigmatism of ≤-0.75 D in optometry clinics in Wenzhou city were analyzed retrospectively. All patients were evaluated until they were 16 years old based on the Correction of Myopia Evaluation Trial (COMET) study.[ 12 ] The longitudinal changes in astigmatism, the factors associated with the changes, and the effects of astigmatism on refraction development were assessed. Methods Study population We retrospectively and inclusively reviewed the clinical records of patients seeking refractive error corrections at Wenzhou Medical University Affiliated Eye Hospital between 2006 and 2018. Patients who were both diagnosed with an astigmatism of ≤-0.75 D in both eyes at 6–10 years old and tracked until the age of 16 years were included. All patients included underwent at least two refractive error evaluations (at the initial visit and at 16 years of age) during this follow-up period. Children with ocular or systemic disorders that are potentially associated with astigmatism and myopia, such as keratoconus and Marfan syndrome, as well as children with chronic eye disorders, such as congenital cataracts and nystagmus, were excluded. Children with a history of wearing corneal contact lenses that may interfere with the characteristics of astigmatism were also excluded. The study was approved by the Ethics Board of Wenzhou Medical University Affiliated Eye Hospital and was performed according to the tenets of the Declaration of Helsinki. Measurements and definitions All patients underwent a comprehensive ophthalmologic examination, which included visual acuity (VA), refraction, slit-lamp, fundoscopy, and orthoptic evaluations, at every follow-up. Refraction was first performed with an autorefractor (KR8800, Topcon Corp, Tokyo, Japan) after cycloplegia, followed by subjective refraction. Cycloplegia was induced with 2 drops of 1% cyclopentolate hydrochloride instilled 5 minutes apart or 1% atropine ointment administered twice a day for three consecutive days. Subjective refractions were performed by 25 optometrists trained to perform assessments with a standardized protocol at Wenzhou Medical University Affiliated Eye Hospital, and the methodology followed was the same as that described in a previous study.[ 13 ] The spherical equivalent (SE) and refractive astigmatism were included in the analyses. SE was calculated as the spherical dioptric power plus one-half of the cylindrical dioptric power. Astigmatism data were analyzed in clinical notation (Cyl, representing the magnitude of astigmatism without regard to the axis) and in vector notation (J0 [Jackson cross-cylinder with axes at 180° and 90°] and J45 [Jackson cross-cylinder with axes at 45° and 135°).[ 14 ] The slope (representing estimated change per year) in the abovementioned refractive errors over the follow-up period was defined as the difference between the final and initial refractive errors divided by the follow-up duration in years. Astigmatism was further classified as WTR (axis between 0 and 15°or between 165 and 180°), against-the-rule (axis between 75 to 105°) and oblique (axis was between 15 and 75° or between 105 and 165°). Data Analysis The data from the right eye were selected for analysis because both astigmatism and SE were highly correlated between the right and left eyes (r = 0.925 and 0.941, respectively, p < 0.001). Paired t-test and X 2 were used to compare refractive errors and astigmatism axis between initial and last visit. One sample t-tests were performed to determine if the mean slope (change/y, D) was significantly different from 0 for each measure of astigmatism (Cyl, J0, and J45). Multivariate analysis of covariance (ANCOVA) was used to determine if slopes for measures of astigmatism and SE differed by the magnitude of the baseline astigmatism measurement (Cyl, low astigmatism [0.75 D to < 1.50 D], moderate astigmatism [1.50 to < 3.00 D], or high astigmatism [≥ 3.00 D]). A second ANCOVA was used to determine if slopes for measures of astigmatism and SE differed by the magnitude of the baseline astigmatism measurement by magnitude of the baseline SE (moderate to high hyperopia [ ≥ + 3.00 D], low hyperopia [+ 0.75 to < + 3.00 D], emmetropia [-0.25 to < + 0.75 D], low myopia [-3.00 to <-0.25 D], or moderate to high myopia [<-3.00 D]). Age at the initial visit and sex were included in ANCOVA as covariates. Multiple linear mixed-effect regression models were used to determine whether the astigmatism measurement, SE, or age at the initial visit or sex were associated with the mean slope in Cyl or SE. Results A total of 3101 patients were included in the analysis (57.3% male; 42.7% female). The median age of the patients at the initial visit was 9 years (IQR: 8–10 years). There were 159 six-year-olds, 389 seven-year-olds, 614 eight-year-olds, 838 nine-year-olds, and 1101 ten-year-olds. All patients were 16 years old at the final visit. The median duration of follow-up was 7 years (IQR, 6–8 years). Twenty nine percent of the patients had refractive evaluation at least once a year, 91.1% had refractive evolution at least once every two years, and 97.5% had refractive evolution at least once every 3 years. Changes in astigmatism and its influencing factors The proportion of WTR astigmatism decreased while the proportion of ATR and oblique astigmatism increased (p < 0.001, Fig. 1 ). The astigmatism measurements at the initial examination and at 16 years of age were presented in Table 1 . On average, Cyl decreased slightly but significantly from the first visit to the last visit (p = 0.034). Cyl increased in children with low astigmatism (p < 0.001) and decreased in children with high astigmatism (p < 0.001). Cyl was stable in children with moderate astigmatism (p = 0.152). J0 decreased and J45 increased from the initial visit to 16 years of age (p < 0.001). A positive slope of Cyl represents an increase in astigmatism magnitude with age, and vice versa. For measurements of J0, a positive slope represents a shift toward an increase in WTR astigmatism and/or a reduction in ATR astigmatism. For measurements of J45, a positive slope represents an increase in astigmatism at axis 135° and/or a reduction in astigmatism at axis 45°. The results of the ANCOVA yielded statistically significant effects of the amount of astigmatism at baseline on the mean Cyl and J0 slope (Table 2 ). With the increase in baseline astigmatism magnitude, both the Cyl and J0 slopes gradually became negative (p < 0.001). There was no significant difference in the J45 slope among different degrees of astigmatism (p = 0.176). In addition, there was no significant effects of axial (WTR, ATR or oblique) on the mean Cyl slope (p = 0.537). The results of the ANCOVA also yielded statistically significant effects of the amount of SE on slopes for measures of astigmatism (Table 2 ). The mean Cyl slopes for the myopic groups were significantly more positive than those for the emmetropia and hyperopic groups (p ≤ 0.001). In the myopic groups, this value for moderate to high myopia was more positive than that for low myopia (p < 0.001). The J0 slope for myopia groups were significantly more positive than that for hyperopia groups (p ≤ 0.032). The J45 slope for the moderate to high hyperopic group was significantly more negative than other groups (p ≤ 0.001). This value for moderate to high myopia was more positive than that for low myopia and emmetropia (p ≤ 0.002). Changes in SE and its influencing factors The mean SE at the initial and last examination was presented in Table 1 . A positive slope represents a decrease (shift toward more myopia with age) in SE and the mean SE slope was 0.54 (0.33) D per year. Table 1 Summary of Sample Characteristics at baseline and the assessment at 16 years of age Variable Initial visit 16 years of age P value Mean Cyl (D) -2.11 (1.18) -2.08 (1.18) 0.034 Low astigmatism -0.98 (0.19) -1.25 (0.65) < 0.001 Moderate astigmatism -1.98 (0.39) -1.95 (0.84) 0.152 High astigmatism -3.78 (0.78) -3.36 (1.05) < 0.001 Mean J0 (D) 1.00 (0.62) 0.94 (0.64) < 0.001 Mean J45 (D) 0.02 (0.29) 0.06 (0.36) < 0.001 WTR (No. %) 2980 (96.1) 2816 (90.8) < 0.001 ATR (No. %) 34 (1.1) 71 (2.3) < 0.001 OBL (No. %) 87 (2.8) 235 (7.6) < 0.001 SE (D) + 0.02 (3.55) -3.29 (4.28) < 0.001 Cyl: cylinder, WTR: with-the-rule axis, ATR: against-the-rule axis, OBL: oblique axis, SE: spherical equivalent The results of the ANCOVA yielded statistically significant effects of the amount of astigmatism at baseline on the mean SE slope (Table 2 ). The mean SE slope for low astigmatism was more positive than for moderate and high astigmatism (p = 0.003). The amount of SE at baseline also had statistically significant effects on the SE slope. The mean SE slopes for myopia groups were more positive than that for emmetropia and hyperopia groups (p = 0.041). The results of the ANCOVA did not show statistically significant effects of axial (WTR, ATR or oblique) on the mean SE slope (p = 0.966). Table 2 Summary of mean astigmatism measurements and SE slope (D/Y) by amount of astigmatism and SE at baseline Amount of astigmatism at baseline n Cyl slope J0 slope J45 slope SE slope 0.75 D to < 1.50 D 1040 0.025 ± 0.03 0.011 ± 0.002 0.05 ± 0.001 0.570 ± 0.010 1.50 to < 3.00 D 1251 -0.008 ± 0.02 -0.009 ± 0.009 0.003 ± 0.002 0.538 ± 0.009 ≥ 3.00 D 801 -0.048 ± 0.03 -0.035 ± 0.002 0.007 ± 0.002 0.519 ± 0.011 p < 0.001 < 0.001 0.176 0.003 Amount of SE at baseline ≥+3.00 D 500 -0.016 ± 0.004 -0.019 ± 0.003 -0.006 ± 0.003 0.530 ± 0.015 + 0.75 to < + 3.00 D 467 -0.023 ± 0.004 -0.018 ± 0.003 -0.004 ± 0.003 0.510 ± 0.015 -0.25 to < + 0.75 D 582 -0.020 ± 0.004 -0.016 ± 0.003 0.008 ± 0.002 0.561 ± 0.013 -3.00 to < -0.25 D 1186 0.000 ± 0.003 -0.004 ± 0.002 0.004 ± 0.002 0.549 ± 0.009 <-3.00 D 366 0.019 ± 0.005 0.004 ± 0.003 0.024 ± 0.003 0.568 ± 0.017 p < 0.001 < 0.001 < 0.001 0.041 Cyl: cylinder, SE: spherical equivalent To investigate the related factors of in slope of Cyl and SE, multivariate linear mixed-effect models were applied to examine age, SE, and Cyl at the initial visit as well as gender (see Table 3 ). The correlation between the initial Cyl or SE and the slope of them were consistent with the above ANCOVA results. Interestingly, gender was related to the rate of change in Cyl (p < 0.001), with girls showing a decrease in Cyl (-0.019 D/y) and boys showing the opposite (0.04 D/y). Figures 2 and 3 show the association between initial cylinder refraction or SE with the slope of astigmatism measurements and SE, respectively. Table 3 Linear mixed-effect models for the associations of the slope for astigmatism and SE with sex and age, astigmatism and SE at the initial visit Cyl slope SE slope Characteristics β (95% CI) p β (95% CI) p Initial Cyl -0.025(-0.028,0.023) < 0.001 -0.019(-0.030, -0.008) 0.001 Initial SE -0.004(-0.005, -0.003) < 0.001 -0.004(-0.007, -0.001) 0.023 Age 0(-0.002,0.002) 0.983 0.059(0.049,0.068) < 0.001 Sex -0.023(-0.029,0.017) < 0.001 0.003(-0.020.0.026) 0.814 Cyl: cylinder, SE: spherical equivalent, CI: confidence interval Discussion The present longitudinal study has the largest sample size and the longest study period among studies investigating the changes in astigmatism as well as the interrelationship between astigmatism and spherical equivalent in Chinese clinical school-age children. We found that children with low baseline astigmatism tended to show an increase in astigmatism with age, whereas children with high baseline astigmatism showed a decrease in astigmatism. Furthermore, astigmatism and spherical equivalents may influence each other’s progression. Similar to earlier studies, WTR astigmatism was predominant in the present study.[ 8 , 15 ] Leung et al.[ 8 ] reported that WTR and ATR astigmatism showed dramatic changes between childhood (3–10 years old) and 60 years of age in Hongkong clinical population, from 92.6–2.7% and from 2.9–79.7%, respectively. They also reported that the proportion of patients with oblique astigmatism changed less dramatically across the age cohorts. The current study tracked the changes in astigmatism in school-age children from 6–10 years of age to 16 years of age. WTR astigmatism and oblique astigmatism change in opposite ways to almost the same extent, while the increase in ATR astigmatism was very slight. Analyzed in junction with the study by Leung et al.[ 8 ], it can be implied that the WTR axis tends to develop toward the oblique axis from childhood to adolescence and later shifts to the ATR axis. Results on the development of astigmatism with age are mixed, and there are very few long-term longitudinal studies of school-age children. Huynh et al.[ 16 ] reported that astigmatism is stable between ages 6 and 12 years. Sherrill et al.[ 17 ] found that highly astigmatic younger children and children older than age 11 years tended to have small increase in astigmatism with age. Tong et al.[ 18 ] investigated the progression in children aged 7 to 9 years over a 4-year period, and found that, astigmatism progressed from 0.44 D to 0.53 D. These studies included children with low astigmatism (about 1 D on average). The children in the present study have higher astigmatism, with an average of about 2 D, probably because the subjects came from optometry clinics. We investigated the effects of baseline astigmatism magnitude on astigmatism progression and found a progression of astigmatism children with low baseline astigmatism of a similar magnitude as in the above study. We also found that children with moderate astigmatism (about 2 D on average) were stable, while those with high astigmatism (about 4 D on average) showed a reduction in astigmatism between the ages of 6–10 and 16 years. As this level of astigmatism has rarely been analyzed longitudinally, it was not possible to compare it with previous studies. In addition to the magnitude of baseline astigmatism, gender could also affect changes in astigmatism. Findings of previous studies on gender differences in astigmatism have been inconsistent. Several studies reported slightly higher prevalence rates of refractive astigmatism in girls than in boys,[ 15 , 19 ] some found the opposite,[ 20 , 21 ] and several other studies reported no gender differences.[ 22 , 23 ] There was no difference in the percentage of boys and girls in the present study. Interestingly, astigmatism decreased in girls but increased in boys during the study period. This is consistent with the results from Tong et al.,[ 18 ] which suggested that the 3-year cumulative incidence rate of astigmatism for boys was slightly higher than that for girls. In contrast, Zhao et al.[ 24 ] reported that cylinder reduction was not associated with gender in multiple regression. More research is needed to determine the results. Additionally, myopic children were found to had increased astigmatism, while nonmyopic children had reduced astigmatism in the current study. Nevertheless, J0 and J45 also tended to progress more in children with higher myopic SE. These results agreed with Tong et al.,[ 18 ] who indicated that the incidence of astigmatism was five times greater in patients with myopia than in those without myopia. Liang et al.[ 25 ] reported a significant increase in astigmatism and myopia in children after studying at home during COVID-19 lockdown. Our findings are in line with these studies, suggesting that myopia may be associated with increased astigmatism. An important objective of this study was to evaluate the effects of basic refraction, especially astigmatism, on the development of refraction. The refraction of children with myopia was found to be changed more than that of children with hyperopia, which implied that the degree of myopia progression in children was greater than the degree of hyperopia regression. This is consistent with previous studies reporting that myopic children have a greater myopic shift than those without myopia.[ 10 , 26 , 27 ] However, a higher magnitude of astigmatism at baseline was associated with less myopia progression the current study, which seems to contradict previous studies. Fulton et al.[ 28 ] found that younger children (< 3 years) with astigmatism tended to have increased myopia. Fan et al.[ 10 ] also reported that the presence of astigmatism, particularly with increasing astigmatism, appeared to predispose preschool children to progressive myopia. Therefore, astigmatism is thought to blur visual images and thus may promote the development of myopia. It is important to note that all of these studies involved preschoolers. Chan et al.[ 9 ] found that subjects without astigmatism had more myopic changes in childhood, which agrees with results from the present study. There are two possible explanations for the present results. First, less astigmatism is associated with more positive SE, which is calculated as sphere plus cylinder. Astigmatism decreased more as the magnitude of basic astigmatism increased in the present study, which may explain the result that children with higher astigmatism experienced less myopic shift. Second, Vyas and Kee [ 29 ] studied the effects of optically imposed astigmatism on myopia development in chickens and found that compared to spherical lenses, the presence of astigmatic blur imposed by sphero-cylindrical lenses induced fewer myopic errors. Nevertheless, chickens that wore high cylinder lenses developed less myopia, which was consistent with results from the present study. If this is true, it could open up new avenues for myopia control. More clinical and animal trials are needed to confirm the results. There are some limitations of the current study. Although each child was followed for a long time, the difference in astigmatic changes between different age groups could not be distinguished because of the retrospective nature of this study and the infrequent follow-up of some patients. Besides, the sample in this study was taken from optometry clinics. On average, these clinics have higher levels of astigmatism than the general population. Despite these limitations, however, the present study is helpful in understanding the longitudinal development of astigmatism and the relationship of astigmatism to spherical equivalent development. Conclusion To summarize, in Chinese clinical school-age children, the longitudinal development of astigmatism from 6–10 to 16 years of age varied with baseline astigmatism. The changes in astigmatism and spherical equivalent were related. The present study supports that the presence of myopia at baseline is a risk factor for astigmatism progression. Interestingly, the higher the basic astigmatism, the slower myopia progression. The present study would support future investigations of clinical interventions for altering the course of increasing astigmatism or to control myopia progression during childhood. Declarations a. Ethics approval and consent to participate The protocol was approved by The Ethics Board of the Wenzhou Medical University Affiliated Eye Hospital and was performed according to the tenets of the Declaration of Helsinki for research involving human subjects. Signed parental informed consent forms were returned to the researchers before examinations were performed on the children. b. Consent for publication Not applicable. c. Availability of data and materials The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. d. Competing interests No competing interests to declare. e. Funding This work was supported by Wenzhou Municipal Science and Technology Bureau (Grant number Y2021k0974). f. Authors' contributions Z.Q. collected and analysed the data. Q.Z. prepared tables and Figures. X.Y. and J.C. revised the manuscript text. W.C. analysed the data and wrote the main manuscript. All authors reviewed the manuscript. 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Ophthalmology. 1982;89(4):298–302. Vyas SA, Kee CS. Early Astigmatism Can Alter Myopia Development in Chickens. Invest Ophthalmol Vis Sci. 2021;62(2):27. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-4010095","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":277393730,"identity":"c4a4e355-586f-49ee-9c26-02db7cf5d035","order_by":0,"name":"Zhuoer Qin","email":"","orcid":"","institution":"Eye Hospital of Wenzhou Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zhuoer","middleName":"","lastName":"Qin","suffix":""},{"id":277393731,"identity":"caae6b5c-bd2b-4598-acdb-9da73c115173","order_by":1,"name":"Qiaolan zheng","email":"","orcid":"","institution":"Eye Hospital of Wenzhou Medical University","correspondingAuthor":false,"prefix":"","firstName":"Qiaolan","middleName":"","lastName":"zheng","suffix":""},{"id":277393732,"identity":"12c0ea4e-9faf-4057-b679-46cc0ae52377","order_by":2,"name":"Xinping Yu","email":"","orcid":"","institution":"Zhongshan Ophthalmic Center of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Xinping","middleName":"","lastName":"Yu","suffix":""},{"id":277393733,"identity":"940eb400-31a7-4bf4-9943-cbf275bea6cc","order_by":3,"name":"Jie Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAnklEQVRIiWNgGAWjYFCCwwdI1nIsgWQtPAYkauBvPPPxMU8Fgzx/A/OzB0RpkThwdrMxzxkGwxkH2MyJs8+A4ew2ad42BsYNDDxsEkRqOfP8N+8/BnuStLAx8zYwJBKvReLAMWPJOcckkmccZjMjTgv/jMMPP7ypsbHtb29+RpwWoDUMTDwMQMXMxKkHWdPAwPiDaNWjYBSMglEwIgEA+L0pJ7lkZaEAAAAASUVORK5CYII=","orcid":"","institution":"Eye Hospital of Wenzhou Medical University","correspondingAuthor":true,"prefix":"","firstName":"Jie","middleName":"","lastName":"Chen","suffix":""},{"id":277393734,"identity":"c3ca427f-a6ac-4140-8cd3-0bd794b92b53","order_by":4,"name":"Wuhe Chen","email":"","orcid":"","institution":"Eye Hospital of Wenzhou Medical University","correspondingAuthor":false,"prefix":"","firstName":"Wuhe","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2024-03-04 01:45:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4010095/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4010095/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52452820,"identity":"40ffbcba-746d-4932-ab5b-94c9270a7db0","added_by":"auto","created_at":"2024-03-11 19:17:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":66277,"visible":true,"origin":"","legend":"\u003cp\u003eThe proportion of with-the-rule, against-the-rule and oblique axes in subjects at the initial visit and at 16 years of age.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4010095/v1/049a18300e4369d544d77d5d.png"},{"id":52452804,"identity":"344a6194-76db-4076-8f41-5d00da497ef6","added_by":"auto","created_at":"2024-03-11 19:17:49","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":42668,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plots show the relationship between cylinder refraction at the initial visit with astigmatism measurements and SE slope. A. The relationship between the initial cylinder refraction and cylinder refraction slope (r=-0.319, p\u0026lt; 0.001). B. The relationship between cylinder refraction at the initial visit and J0 slope (r=0.025, p=0.167.). C. Therelationship between cylinder refraction at the initial visit and J45 slope (r=0.211, p\u0026lt;0.001). D. Therelationship between cylinder refraction at the initial visit and SE slope (r=-0.059, p=0.001).\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4010095/v1/035f1b6dcd1232ed7764825a.png"},{"id":52452767,"identity":"f910e927-554f-4fbd-bbba-4ef20c4f410f","added_by":"auto","created_at":"2024-03-11 19:17:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":59131,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plots show the relationship between SE at the initial visit with astigmatism measurements and the SE slope. A. Therelationship between the SE at the initial visit and cylinder refraction slope (r=-0.088, p\u0026lt;0.001). B. The relationship between SE at the initial visit and J0 slope (r=-0.006, p=0.722). C. Therelationship between SE at the initial visit and J45 slope (r=-0.095, p\u0026lt;0.001). D. The relationship between SE at the initial visit and SE slope (r=-0.058, p=0.001).\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4010095/v1/4b46129a0511cdd6cae5b1c5.png"},{"id":84522736,"identity":"7181ea69-1448-4f2c-8fb9-81f1074ef853","added_by":"auto","created_at":"2025-06-13 04:08:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":855425,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4010095/v1/d0740868-6128-46a6-bd1c-95c4e44b76be.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Long-term longitudinal changes in astigmatism and their effect on refraction development in Chinese clinical school-age children","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAstigmatism is a highly prevalent refractive error worldwide, frequently coexisting with myopia and hyperopia. There have been population-based reports on the prevalence of astigmatism in children from different ethnic groups, and the prevalence of astigmatism in school-aged children is generally higher in East Asian populations than in other ethnicities.[\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] Eyelid pressure is most likely to be involved in the development of corneal astigmatism.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] Higher lid tension in Asian populations is suggested to be an associated factor leading to a higher prevalence of astigmatism.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] Eyelid pressure should change as children age, and the long-term trend of astigmatism in children is not clear.\u003c/p\u003e \u003cp\u003eIn addition, Gwiazda et al.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] analyzed the functional significance of astigmatism in emmetropization and the development of myopia, finding that infantile astigmatism is associated with increased astigmatism and myopia in childhood. Furthermore, the association of high prevalence of astigmatism and increasing myopia in school-age Asian populations raises the question of whether the presence of astigmatism contributes to the development of myopia.\u003csup\u003e[8]\u003c/sup\u003e A few studies have investigated longitudinal changes in refractive astigmatism and their effects on refractive development in children. Most of these studies are short-term and the majority of them focused on pre-school children. For example, Chan et al.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] studied the progression of astigmatism in primary school children and its effect on myopic shift in southern Taiwan over a 1-year period. They found that the astigmatism decreased during the one-year follow-up and was not associated with myopia progression. Fan et al.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] studied the progression of astigmatism and its effect on refractive development in preschool children in Hong Kong with a follow-up of 55.7 months. They reported that a significant percentage of children had stable and even increased astigmatism. In addition, children with increased astigmatism had greater myopic progression.\u003c/p\u003e \u003cp\u003eThe incidences of both astigmatism and myopia are very high in school-age children in southern China.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] However, the developmental interplay between the two has not been explored in this population. In this study, data collected in a large cohort with astigmatism of \u0026le;-0.75 D in optometry clinics in Wenzhou city were analyzed retrospectively. All patients were evaluated until they were 16 years old based on the Correction of Myopia Evaluation Trial (COMET) study.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] The longitudinal changes in astigmatism, the factors associated with the changes, and the effects of astigmatism on refraction development were assessed.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e \u003cb\u003eStudy population\u003c/b\u003e \u003c/p\u003e \u003cp\u003eWe retrospectively and inclusively reviewed the clinical records of patients seeking refractive error corrections at Wenzhou Medical University Affiliated Eye Hospital between 2006 and 2018. Patients who were both diagnosed with an astigmatism of \u0026le;-0.75 D in both eyes at 6\u0026ndash;10 years old and tracked until the age of 16 years were included. All patients included underwent at least two refractive error evaluations (at the initial visit and at 16 years of age) during this follow-up period. Children with ocular or systemic disorders that are potentially associated with astigmatism and myopia, such as keratoconus and Marfan syndrome, as well as children with chronic eye disorders, such as congenital cataracts and nystagmus, were excluded. Children with a history of wearing corneal contact lenses that may interfere with the characteristics of astigmatism were also excluded. The study was approved by the Ethics Board of Wenzhou Medical University Affiliated Eye Hospital and was performed according to the tenets of the Declaration of Helsinki.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMeasurements and definitions\u003c/b\u003e \u003c/p\u003e \u003cp\u003eAll patients underwent a comprehensive ophthalmologic examination, which included visual acuity (VA), refraction, slit-lamp, fundoscopy, and orthoptic evaluations, at every follow-up. Refraction was first performed with an autorefractor (KR8800, Topcon Corp, Tokyo, Japan) after cycloplegia, followed by subjective refraction. Cycloplegia was induced with 2 drops of 1% cyclopentolate hydrochloride instilled 5 minutes apart or 1% atropine ointment administered twice a day for three consecutive days. Subjective refractions were performed by 25 optometrists trained to perform assessments with a standardized protocol at Wenzhou Medical University Affiliated Eye Hospital, and the methodology followed was the same as that described in a previous study.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe spherical equivalent (SE) and refractive astigmatism were included in the analyses. SE was calculated as the spherical dioptric power plus one-half of the cylindrical dioptric power. Astigmatism data were analyzed in clinical notation (Cyl, representing the magnitude of astigmatism without regard to the axis) and in vector notation (J0 [Jackson cross-cylinder with axes at 180\u0026deg; and 90\u0026deg;] and J45 [Jackson cross-cylinder with axes at 45\u0026deg; and 135\u0026deg;).[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] The slope (representing estimated change per year) in the abovementioned refractive errors over the follow-up period was defined as the difference between the final and initial refractive errors divided by the follow-up duration in years. Astigmatism was further classified as WTR (axis between 0 and 15\u0026deg;or between 165 and 180\u0026deg;), against-the-rule (axis between 75 to 105\u0026deg;) and oblique (axis was between 15 and 75\u0026deg; or between 105 and 165\u0026deg;).\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cp\u003eThe data from the right eye were selected for analysis because both astigmatism and SE were highly correlated between the right and left eyes (r\u0026thinsp;=\u0026thinsp;0.925 and 0.941, respectively, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Paired t-test and X\u003csup\u003e2\u003c/sup\u003e were used to compare refractive errors and astigmatism axis between initial and last visit. One sample t-tests were performed to determine if the mean slope (change/y, D) was significantly different from 0 for each measure of astigmatism (Cyl, J0, and J45). Multivariate analysis of covariance (ANCOVA) was used to determine if slopes for measures of astigmatism and SE differed by the magnitude of the baseline astigmatism measurement (Cyl, low astigmatism [0.75 D to \u0026lt;\u0026thinsp;1.50 D], moderate astigmatism [1.50 to \u0026lt;\u0026thinsp;3.00 D], or high astigmatism [\u0026ge;\u0026thinsp;3.00 D]). A second ANCOVA was used to determine if slopes for measures of astigmatism and SE differed by the magnitude of the baseline astigmatism measurement by magnitude of the baseline SE (moderate to high hyperopia [\u0026thinsp;\u0026ge;\u0026thinsp;+\u0026thinsp;3.00 D], low hyperopia [+\u0026thinsp;0.75 to \u0026lt;\u0026thinsp;+\u0026thinsp;3.00 D], emmetropia [-0.25 to \u0026lt;\u0026thinsp;+\u0026thinsp;0.75 D], low myopia [-3.00 to \u0026lt;-0.25 D], or moderate to high myopia [\u0026lt;-3.00 D]). Age at the initial visit and sex were included in ANCOVA as covariates. Multiple linear mixed-effect regression models were used to determine whether the astigmatism measurement, SE, or age at the initial visit or sex were associated with the mean slope in Cyl or SE.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 3101 patients were included in the analysis (57.3% male; 42.7% female). The median age of the patients at the initial visit was 9 years (IQR: 8\u0026ndash;10 years). There were 159 six-year-olds, 389 seven-year-olds, 614 eight-year-olds, 838 nine-year-olds, and 1101 ten-year-olds. All patients were 16 years old at the final visit. The median duration of follow-up was 7 years (IQR, 6\u0026ndash;8 years). Twenty nine percent of the patients had refractive evaluation at least once a year, 91.1% had refractive evolution at least once every two years, and 97.5% had refractive evolution at least once every 3 years.\u003c/p\u003e \u003cp\u003e \u003cb\u003eChanges in astigmatism and its influencing factors\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe proportion of WTR astigmatism decreased while the proportion of ATR and oblique astigmatism increased (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The astigmatism measurements at the initial examination and at 16 years of age were presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. On average, Cyl decreased slightly but significantly from the first visit to the last visit (p\u0026thinsp;=\u0026thinsp;0.034). Cyl increased in children with low astigmatism (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and decreased in children with high astigmatism (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Cyl was stable in children with moderate astigmatism (p\u0026thinsp;=\u0026thinsp;0.152). J0 decreased and J45 increased from the initial visit to 16 years of age (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eA positive slope of Cyl represents an increase in astigmatism magnitude with age, and vice versa. For measurements of J0, a positive slope represents a shift toward an increase in WTR astigmatism and/or a reduction in ATR astigmatism. For measurements of J45, a positive slope represents an increase in astigmatism at axis 135\u0026deg; and/or a reduction in astigmatism at axis 45\u0026deg;. The results of the ANCOVA yielded statistically significant effects of the amount of astigmatism at baseline on the mean Cyl and J0 slope (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). With the increase in baseline astigmatism magnitude, both the Cyl and J0 slopes gradually became negative (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). There was no significant difference in the J45 slope among different degrees of astigmatism (p\u0026thinsp;=\u0026thinsp;0.176). In addition, there was no significant effects of axial (WTR, ATR or oblique) on the mean Cyl slope (p\u0026thinsp;=\u0026thinsp;0.537).\u003c/p\u003e \u003cp\u003eThe results of the ANCOVA also yielded statistically significant effects of the amount of SE on slopes for measures of astigmatism (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The mean Cyl slopes for the myopic groups were significantly more positive than those for the emmetropia and hyperopic groups (p\u0026thinsp;\u0026le;\u0026thinsp;0.001). In the myopic groups, this value for moderate to high myopia was more positive than that for low myopia (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The J0 slope for myopia groups were significantly more positive than that for hyperopia groups (p\u0026thinsp;\u0026le;\u0026thinsp;0.032). The J45 slope for the moderate to high hyperopic group was significantly more negative than other groups (p\u0026thinsp;\u0026le;\u0026thinsp;0.001). This value for moderate to high myopia was more positive than that for low myopia and emmetropia (p\u0026thinsp;\u0026le;\u0026thinsp;0.002).\u003c/p\u003e \u003cp\u003e \u003cb\u003eChanges in SE and its influencing factors\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe mean SE at the initial and last examination was presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A positive slope represents a decrease (shift toward more myopia with age) in SE and the mean SE slope was 0.54 (0.33) D per year.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of Sample Characteristics at baseline and the assessment at 16 years of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial visit\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16 years of age\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Cyl (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-2.11 (1.18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-2.08 (1.18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.034\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow astigmatism\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.98 (0.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-1.25 (0.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerate astigmatism\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-1.98 (0.39)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-1.95 (0.84)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.152\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh astigmatism\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-3.78 (0.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-3.36 (1.05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean J0 (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.00 (0.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.94 (0.64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean J45 (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.02 (0.29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.06 (0.36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWTR (No. %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2980 (96.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2816 (90.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eATR (No. %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e34 (1.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e71 (2.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOBL (No. %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e87 (2.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e235 (7.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSE (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e+\u0026thinsp;0.02 (3.55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-3.29 (4.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eCyl: cylinder, WTR: with-the-rule axis, ATR: against-the-rule axis, OBL: oblique axis, SE: spherical equivalent\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe results of the ANCOVA yielded statistically significant effects of the amount of astigmatism at baseline on the mean SE slope (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The mean SE slope for low astigmatism was more positive than for moderate and high astigmatism (p\u0026thinsp;=\u0026thinsp;0.003). The amount of SE at baseline also had statistically significant effects on the SE slope. The mean SE slopes for myopia groups were more positive than that for emmetropia and hyperopia groups (p\u0026thinsp;=\u0026thinsp;0.041). The results of the ANCOVA did not show statistically significant effects of axial (WTR, ATR or oblique) on the mean SE slope (p\u0026thinsp;=\u0026thinsp;0.966).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of mean astigmatism measurements and SE slope (D/Y) by amount of astigmatism and SE at baseline\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAmount of astigmatism at baseline\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCyl slope\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eJ0 slope\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eJ45 slope\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSE slope\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0.75 D to \u0026lt;\u0026thinsp;1.50 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1040\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.025\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.011\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.570\u0026thinsp;\u0026plusmn;\u0026thinsp;0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.50 to \u0026lt;\u0026thinsp;3.00 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.008\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.009\u0026thinsp;\u0026plusmn;\u0026thinsp;0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.003\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.538\u0026thinsp;\u0026plusmn;\u0026thinsp;0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;3.00 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e801\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.048\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.035\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.007\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.519\u0026thinsp;\u0026plusmn;\u0026thinsp;0.011\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.176\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAmount of SE at baseline\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;+3.00 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.016\u0026thinsp;\u0026plusmn;\u0026thinsp;0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.019\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.006\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.530\u0026thinsp;\u0026plusmn;\u0026thinsp;0.015\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e+\u0026thinsp;0.75 to \u0026lt;\u0026thinsp;+\u0026thinsp;3.00 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e467\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.023\u0026thinsp;\u0026plusmn;\u0026thinsp;0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.018\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.004\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.510\u0026thinsp;\u0026plusmn;\u0026thinsp;0.015\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e-0.25 to \u0026lt;\u0026thinsp;+\u0026thinsp;0.75 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e582\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.020\u0026thinsp;\u0026plusmn;\u0026thinsp;0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.016\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.008\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.561\u0026thinsp;\u0026plusmn;\u0026thinsp;0.013\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e-3.00 to \u0026lt; -0.25 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1186\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.000\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.004\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.004\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.549\u0026thinsp;\u0026plusmn;\u0026thinsp;0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;-3.00 D\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e366\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.019\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.004\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.024\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.568\u0026thinsp;\u0026plusmn;\u0026thinsp;0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eCyl: cylinder, SE: spherical equivalent\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTo investigate the related factors of in slope of Cyl and SE, multivariate linear mixed-effect models were applied to examine age, SE, and Cyl at the initial visit as well as gender (see Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The correlation between the initial Cyl or SE and the slope of them were consistent with the above ANCOVA results. Interestingly, gender was related to the rate of change in Cyl (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with girls showing a decrease in Cyl (-0.019 D/y) and boys showing the opposite (0.04 D/y). Figures\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e show the association between initial cylinder refraction or SE with the slope of astigmatism measurements and SE, respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLinear mixed-effect models for the associations of the slope for astigmatism and SE with sex and age, astigmatism and SE at the initial visit\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCyl slope\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eSE slope\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eβ (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eβ (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInitial Cyl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.025(-0.028,0.023)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.019(-0.030, -0.008)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInitial SE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.004(-0.005, -0.003)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.004(-0.007, -0.001)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.023\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(-0.002,0.002)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.983\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.059(0.049,0.068)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.023(-0.029,0.017)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.003(-0.020.0.026)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.814\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eCyl: cylinder, SE: spherical equivalent, CI: confidence interval\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e "},{"header":"Discussion","content":"\u003cp\u003eThe present longitudinal study has the largest sample size and the longest study period among studies investigating the changes in astigmatism as well as the interrelationship between astigmatism and spherical equivalent in Chinese clinical school-age children. We found that children with low baseline astigmatism tended to show an increase in astigmatism with age, whereas children with high baseline astigmatism showed a decrease in astigmatism. Furthermore, astigmatism and spherical equivalents may influence each other\u0026rsquo;s progression.\u003c/p\u003e \u003cp\u003eSimilar to earlier studies, WTR astigmatism was predominant in the present study.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] Leung et al.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] reported that WTR and ATR astigmatism showed dramatic changes between childhood (3\u0026ndash;10 years old) and 60 years of age in Hongkong clinical population, from 92.6\u0026ndash;2.7% and from 2.9\u0026ndash;79.7%, respectively. They also reported that the proportion of patients with oblique astigmatism changed less dramatically across the age cohorts. The current study tracked the changes in astigmatism in school-age children from 6\u0026ndash;10 years of age to 16 years of age. WTR astigmatism and oblique astigmatism change in opposite ways to almost the same extent, while the increase in ATR astigmatism was very slight. Analyzed in junction with the study by Leung et al.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], it can be implied that the WTR axis tends to develop toward the oblique axis from childhood to adolescence and later shifts to the ATR axis.\u003c/p\u003e \u003cp\u003eResults on the development of astigmatism with age are mixed, and there are very few long-term longitudinal studies of school-age children. Huynh et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] reported that astigmatism is stable between ages 6 and 12 years. Sherrill et al.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] found that highly astigmatic younger children and children older than age 11 years tended to have small increase in astigmatism with age. Tong et al.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] investigated the progression in children aged 7 to 9 years over a 4-year period, and found that, astigmatism progressed from 0.44 D to 0.53 D. These studies included children with low astigmatism (about 1 D on average). The children in the present study have higher astigmatism, with an average of about 2 D, probably because the subjects came from optometry clinics. We investigated the effects of baseline astigmatism magnitude on astigmatism progression and found a progression of astigmatism children with low baseline astigmatism of a similar magnitude as in the above study. We also found that children with moderate astigmatism (about 2 D on average) were stable, while those with high astigmatism (about 4 D on average) showed a reduction in astigmatism between the ages of 6\u0026ndash;10 and 16 years. As this level of astigmatism has rarely been analyzed longitudinally, it was not possible to compare it with previous studies.\u003c/p\u003e \u003cp\u003eIn addition to the magnitude of baseline astigmatism, gender could also affect changes in astigmatism. Findings of previous studies on gender differences in astigmatism have been inconsistent. Several studies reported slightly higher prevalence rates of refractive astigmatism in girls than in boys,[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] some found the opposite,[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and several other studies reported no gender differences.[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] There was no difference in the percentage of boys and girls in the present study. Interestingly, astigmatism decreased in girls but increased in boys during the study period. This is consistent with the results from Tong et al.,[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] which suggested that the 3-year cumulative incidence rate of astigmatism for boys was slightly higher than that for girls. In contrast, Zhao et al.[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] reported that cylinder reduction was not associated with gender in multiple regression. More research is needed to determine the results.\u003c/p\u003e \u003cp\u003eAdditionally, myopic children were found to had increased astigmatism, while nonmyopic children had reduced astigmatism in the current study. Nevertheless, J0 and J45 also tended to progress more in children with higher myopic SE. These results agreed with Tong et al.,[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] who indicated that the incidence of astigmatism was five times greater in patients with myopia than in those without myopia. Liang et al.[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] reported a significant increase in astigmatism and myopia in children after studying at home during COVID-19 lockdown. Our findings are in line with these studies, suggesting that myopia may be associated with increased astigmatism.\u003c/p\u003e \u003cp\u003eAn important objective of this study was to evaluate the effects of basic refraction, especially astigmatism, on the development of refraction. The refraction of children with myopia was found to be changed more than that of children with hyperopia, which implied that the degree of myopia progression in children was greater than the degree of hyperopia regression. This is consistent with previous studies reporting that myopic children have a greater myopic shift than those without myopia.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] However, a higher magnitude of astigmatism at baseline was associated with less myopia progression the current study, which seems to contradict previous studies. Fulton et al.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] found that younger children (\u0026lt;\u0026thinsp;3 years) with astigmatism tended to have increased myopia. Fan et al.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] also reported that the presence of astigmatism, particularly with increasing astigmatism, appeared to predispose preschool children to progressive myopia. Therefore, astigmatism is thought to blur visual images and thus may promote the development of myopia. It is important to note that all of these studies involved preschoolers. Chan et al.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] found that subjects without astigmatism had more myopic changes in childhood, which agrees with results from the present study. There are two possible explanations for the present results. First, less astigmatism is associated with more positive SE, which is calculated as sphere plus cylinder. Astigmatism decreased more as the magnitude of basic astigmatism increased in the present study, which may explain the result that children with higher astigmatism experienced less myopic shift. Second, Vyas and Kee [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] studied the effects of optically imposed astigmatism on myopia development in chickens and found that compared to spherical lenses, the presence of astigmatic blur imposed by sphero-cylindrical lenses induced fewer myopic errors. Nevertheless, chickens that wore high cylinder lenses developed less myopia, which was consistent with results from the present study. If this is true, it could open up new avenues for myopia control. More clinical and animal trials are needed to confirm the results.\u003c/p\u003e \u003cp\u003eThere are some limitations of the current study. Although each child was followed for a long time, the difference in astigmatic changes between different age groups could not be distinguished because of the retrospective nature of this study and the infrequent follow-up of some patients. Besides, the sample in this study was taken from optometry clinics. On average, these clinics have higher levels of astigmatism than the general population. Despite these limitations, however, the present study is helpful in understanding the longitudinal development of astigmatism and the relationship of astigmatism to spherical equivalent development.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eTo summarize, in Chinese clinical school-age children, the longitudinal development of astigmatism from 6\u0026ndash;10 to 16 years of age varied with baseline astigmatism. The changes in astigmatism and spherical equivalent were related. The present study supports that the presence of myopia at baseline is a risk factor for astigmatism progression. Interestingly, the higher the basic astigmatism, the slower myopia progression. The present study would support future investigations of clinical interventions for altering the course of increasing astigmatism or to control myopia progression during childhood.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003ea. Ethics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe protocol was approved by The Ethics Board of the\u0026nbsp;Wenzhou Medical University Affiliated Eye Hospital and was performed according to the tenets of the Declaration of Helsinki for research involving human subjects. Signed parental informed consent forms were returned to the researchers before examinations were performed on the children.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb. Consent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec. Availability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed. Competing interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo competing interests to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ee. Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Wenzhou Municipal Science and Technology Bureau (Grant\u0026nbsp;number Y2021k0974).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ef. Authors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZ.Q. collected and analysed the data. Q.Z. prepared tables and Figures. X.Y. and J.C. revised the manuscript text. W.C. analysed the data and wrote the main manuscript. All authors reviewed the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDandona R, Dandona L, Naduvilath TJ, Srinivas M, McCarty CA, Rao GN. Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study. Invest Ophthalmol Vis Sci. 1999;40(12):2810\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe M, Zeng J, Liu Y, Xu J, Pokharel GP, Ellwein LB. Refractive error and visual impairment in urban children in southern china. Invest Ophthalmol Vis Sci. 2004;45(3):793\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKleinstein RN, Jones LA, Hullett S, Kwon S, Lee RJ, Friedman NE, Manny RE, Mutti DO, Yu JA, Zadnik K, et al. Refractive error and ethnicity in children. Arch Ophthalmol. 2003;121(8):1141\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShih YF, Hsiao CK, Tung YL, Lin LL, Chen CJ, Hung PT. 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Prevalence rates and epidemiological risk factors for astigmatism in Singapore school children. Optom Vis Sci. 2002;79(9):606\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao J, Mao J, Luo R, Li F, Munoz SR, Ellwein LB. The progression of refractive error in school-age children: Shunyi district, China. Am J Ophthalmol. 2002;134(5):735\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang Y, Leung TW, Lian JT, Kee CS. Significant increase in astigmatism in children after study at home during the COVID-19 lockdown. Clin Exp Optom 2022:1\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatanabe S, Yamashita T, Ohba N. A longitudinal study of cycloplegic refraction in a cohort of 350 Japanese schoolchildren. Cycloplegic refraction. 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Invest Ophthalmol Vis Sci. 2021;62(2):27.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"astigmatism, spherical equivalent, refraction development, school-age children","lastPublishedDoi":"10.21203/rs.3.rs-4010095/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4010095/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eTo investigate longitudinal changes in astigmatism in Chinese clinical school-age children and to explore the effect of astigmatism on refraction development.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThe medical records of patients with long-term follow-up data from 2006 to 2018 were retrospectively reviewed. Patients who were 6\u0026ndash;10 years old at initial visit and 16 years old at last assessment were selected for analysis. The enrolled patients had a cylinder refraction of 0.75 or greater. Astigmatism was analyzed in clinical notation and vector notation (J0, J45). The related factors of changes in astigmatism and spherical equivalent per year and the interaction between the two were analyzed.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eA total of 3101 patients (median age 9 years at initial visit) were followed up for an average of 7 years (IQR, 6\u0026ndash;8 years). Astigmatism increased with age in low astigmats (\u0026lt;\u0026thinsp;1.50 D, 0.025 D/y) and decreased with age in high astigmats (\u0026ge;\u0026thinsp;3.00 D, -0.048 D/y). The oblique astigmatism (J45, 0.005D/y) increased and with-the-rule (WTR) astigmatism (J0, -0.008D/y) decreased. Higher myopia of the SE at the initial visit was associated with a greater increase in astigmatism magnitude(p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A higher magnitude of initial astigmatism was associated with less progression in spherical equivalent(p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eIn Chinese clinical school-age children, the longitudinal development of astigmatism from 6\u0026ndash;10 to 16 years of age varied with baseline astigmatism. The presence of myopia at baseline was a risk factor for astigmatism progression. However, high astigmatism seems to prevent the progression of myopia.\u003c/p\u003e","manuscriptTitle":"Long-term longitudinal changes in astigmatism and their effect on refraction development in Chinese clinical school-age children","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-11 19:16:35","doi":"10.21203/rs.3.rs-4010095/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"951befb4-6fd0-4335-b6c1-51acaf30a139","owner":[],"postedDate":"March 11th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-13T04:08:25+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-11 19:16:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4010095","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4010095","identity":"rs-4010095","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}