Association between dry eye symptoms and upper-eyelid position in Korean adults: A nationwide population-based study

Association between dry eye symptoms and upper-eyelid position in Korean adults: A nationwide population-based study | 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 Article Association between dry eye symptoms and upper-eyelid position in Korean adults: A nationwide population-based study Sun Young Jang, Yeseul Kim, Sung Chul Park, Sangsoo Han This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7015840/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract BACKGROUND To investigate the association between dry eye symptoms and upper-eyelid position in a nationally representative Korean population. METHODS Data from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted between 2010 and 2012 were analysed to assess the relationship between upper-eyelid position and the presence of dry eye symptoms. In total, 11,385 subjects aged 40 years or older were included, and multiple logistic regression was performed to adjust for potential confounders. Sampling weights were applied to obtain estimates for the general Korean population. RESULTS Patients with dry eye symptoms were more likely to be women, non-smokers, and non-drinkers, and were more commonly residents of urban areas. They also had elevated marginal reflex distance 1 (MRD1) values and a higher prevalence of hypertension, depressive disorder, hyperlipidaemia, and thyroid diseases. An increase in MRD1 was significantly associated with higher odds of experiencing dry eye symptoms in both the right and left eyes ( P = 0.0043 and P = 0.0055, respectively). CONCLUSIONS Increased MRD1 was significantly associated with dry eye symptoms in a representative Korean population. These findings imply that dry eye symptoms can potentially worsen after upper-eyelid surgeries, including ptosis correction, and should be considered during preoperative evaluation and counselling. Health sciences/Signs and symptoms/Eye manifestations Health sciences/Risk factors Health sciences/Medical research/Epidemiology Figures Figure 1 Figure 2 SUMMARY What was known before Dry eye disease (DED) is influenced by numerous factors such as age, sex, digital device use, and prior ocular surgery. Eyelid position may affect tear dynamics, but evidence linking marginal reflex distance 1 to dry eye symptoms is inconsistent. Objective tests for DED are often poorly correlated with patient-reported symptoms. What this study adds This is the first population-based study to show a significant association between higher MRD1 values and self-reported dry eye symptoms. The findings highlight the role of eyelid position in symptom perception, independent of clinical DED diagnosis. The results emphasize the need to consider patient-reported outcomes when evaluating or planning eyelid surgery. INTRODUCTION Dry eye disease (DED) is a multifactorial disorder of the ocular surface characterized by disruption of tear film homeostasis, leading to ocular discomfort, visual disturbance, and reduced quality of life [ 1 , 2 ]. Well-established risk factors for DED include advanced age, female sex, digital device use, and a history of ocular surgery [ 3 – 6 ]. In addition, recent studies have suggested that eyelid anatomy and function may also play roles in maintaining ocular surface stability. In particular, acquired aponeurogenic blepharoptosis is associated with altered tear dynamics and a higher prevalence of DED [ 7 ]. Patients with acquired blepharoptosis often demonstrate reduced tear production as measured by the Schirmer test [ 7 ]. However, it remains unclear whether the decreased tear production contributes to the development of ptosis or simply reflects diminished reflex tearing secondary to the ptotic eyelid. Conversely, several clinical studies have reported changes in dry eye parameters following ptosis correction procedures, such as levator advancement or Müller muscle-conjunctival resection (MMCR), including changes in tear breakup time, corneal staining, and Schirmer test scores [ 8 – 11 ]. Notably, long-term follow-up studies have shown that patients undergoing MMCR, but not those undergoing upper blepharoplasty, may experience a worsening of dry eye signs compared to their preoperative status [ 10 ]. Although the potential influence of eyelid position on ocular surface homeostasis is increasingly acknowledged, the findings remain inconsistent. It is still unclear whether eyelid position directly affects tear film stability or is associated simply through shared age-related factors. To the best of our knowledge, no previous study has quantitatively assessed the relationship between upper-eyelid position, commonly measured by marginal reflex distance 1 (MRD1), and subjective dry eye symptoms in a large-scale population-based setting. Therefore, this study used a nationally representative health survey to investigate the association between MRD1—as a surrogate marker of eyelid aperture—and self-reported symptoms of dry eye. MATERIALS AND METHODS Study design and participants We used data from the Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide, cross-sectional survey conducted by the Korea Centers for Disease Control and Prevention (KCDC) since 1998 [ 12 ]. The KNHANES collects comprehensive health-related data through interviews, self-administered questionnaires, physical examinations, and dietary assessments. It adopts a stratified, multistage probability sampling method based on household registries, with sampling stratified by geographic region, sex, and age. Each year, approximately 10,000 individuals are sampled from 192 primary sampling units, which are defined by administrative districts and housing characteristics. We focused on individuals aged 40 years and older who participated in the fifth KNHANES conducted from 2010 to 2012. Participants were excluded if they did not complete the ophthalmologic examination or failed to respond to key survey items used in this study. Ophthalmologic examination Ophthalmologic data were obtained through mobile examination units operated by board-certified ophthalmologists dispatched by the Korean Ophthalmological Society. Dry eye symptoms were evaluated based on self-reported responses. Participants were asked, “Have you ever experienced symptoms of dry eyes, such as a sensation of dryness or irritation?” Responses were recorded as either “yes” or “no,” and only self-reported symptom data were used in the analysis. MRD1 was measured as the vertical distance from the corneal light reflex to the upper-eyelid margin in the primary gaze position, excluding the influence of dermatochalasis or brow ptosis. MRD1 values were categorized into five descending groups: < 1.0 mm, 1.0–1.9 mm, 2.0–2.9 mm, 3.0–3.9 mm, and ≥ 4.0 mm. Potential mediators and confounders Data on demographic characteristics, socioeconomic indicators, medical history, and lifestyle behaviours were obtained through health interviews and physical examinations. Body mass index was calculated as weight in kilograms divided by height in meters squared (kg/m 2 ). Participants were classified into two categories based on smoking status: current smokers and non-current smokers, the latter including both never and former smokers. Alcohol consumption was stratified into four groups: none, ≤ 1 drink per month, 2–3 drinks per week, and ≥ 4 drinks per week. Educational attainment was categorized into elementary school, middle school, high school, and college/university. Household income was divided into quartiles. Sleep duration was assessed by asking participants, “How many hours do you sleep each day?” Perceived stress was assessed using the question, “How stressed do you feel on a typical day?” Responses were categorized into four levels: none, mild (slightly stressed), moderate (moderately stressed), and severe (extremely stressed). Participants were also evaluated for the presence of comorbid conditions, including hypertension, diabetes mellitus, hypercholesterolaemia, rheumatoid arthritis, depression, history of ocular surgery, and thyroid disorders. Statistical analysis Categorical variables were compared using the chi-square test, while continuous variables were analysed using independent samples t -tests. To estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs), logistic regression models were employed. We constructed three models to explore potential mediators and confounders. Model 1 was unadjusted. Model 2 was adjusted for age and sex. Model 3 was fully adjusted for age, sex, area of residence, education level, body mass index, smoking, drinking, stress perception, sun exposure, income, hypertension, diabetes mellitus, depression, rheumatoid arthritis, hypercholesterolaemia, thyroid abnormality, duration of sleep, and history of ocular surgery. Given the complex sampling design of the KNHANES dataset, all statistical analyses accounted for its multistage probability structure and incorporated survey weights to ensure nationally representative estimates. All analyses were performed using IBM SPSS Statistics for Windows, version 26.0 (IBM Corp., Armonk, NY, USA) and Python (version 3.12). A two-sided P -value of less than 0.05 was considered to indicate statistical significance. Ethics statement The Institutional Review Board of the Korea Centers for Disease Control and Prevention approved the KNHANES V (approval no. 2010-02CON-21-C), and all participants provided informed consent. The study followed the principles of the Declaration of Helsinki and complied with all relevant guidelines and regulations. RESULTS In all, 24,173 individuals participated in the KNHANES from 2010 to 2012. After excluding participants under 40 years of age (n = 10,919), 13,254 individuals remained. Among them, 1031 individuals who did not undergo ophthalmologic examination were excluded, resulting in 12,223 participants. Subsequently, 838 individuals with incomplete data were further excluded. The final analysis included 11,385 participants (Fig. 1). Baseline characteristics according to dry eye symptoms Among the 11,385 participants, 1964 individuals (17.3%) reported having dry eye symptoms, while 9421 (82.7%) did not. Table 1 presents the baseline characteristics according to dry eye symptom status. Participants with symptoms were significantly ( P < 0.001) more likely to be female (71.7% vs. 54.2%), older (60.3 ± 11.0 years vs. 59.3 ± 11.3 years), to reside in an urban area (68.3% vs. 62.5%), and to have thyroid abnormalities (7.6% vs. 4.3%), hypercholesterolaemia (18.7% vs. 13.1%), a history of ocular surgery (23.3% vs. 14.6%), shorter mean sleep duration (6.5 ± 1.5 h vs. 6.7 ± 1.5 h), and less perceived stress. Sun exposure times also differed significantly between the groups: 63.0% of individuals with symptoms reported being exposed to sunlight for ≤ 2 h per day compared to 59.5% in the asymptomatic group; the values were 14.2% and 17.4%, respectively, for ≥ 5 h sun exposure. The distribution of MRD1 values also differed significantly between the groups. In the right eye, 25.9% of participants with symptoms had an MRD1 value of less than 1 mm compared to 29.5% of those without symptoms, and 4.5% of individuals with symptoms had an MRD1 value ≥ 4 mm compared to 3.7% of the non-dry eye group. Similar differences were observed in the left eye, with 25.6% in the dry eye group having an MRD1 value < 1 mm vs. 29.4% in the control group, and 4.0% vs. 3.8%, respectively, having an MRD1 value ≥ 4 mm. Relationship between upper-eyelid position and dry eye symptoms The association between MRD1 values and the presence of dry eye symptoms is summarized in Table 2 and illustrated in Figure 2. In the unadjusted and partially adjusted models (Models 1 and 2), increasing MRD1 values in both eyes were associated with higher odds of symptoms. This trend persisted after full adjustment for multiple demographic, behavioural, and clinical covariates in Model 3. In the fully adjusted model, individuals with right eye MRD1 values of 1–1.9 mm and 2–2.9 mm had significantly increased odds of symptoms compared to those with MRD1 values of < 1 mm, with ORs of 1.24 and 1.28, respectively (see the table for CI values). Participants in the highest MRD1 category (≥ 4 mm) also had an elevated OR (OR = 1.65). In the left eye, a significant association was found only in the 2–2.9 mm group (OR = 1.31). Although not all categories reached statistical significance, particularly in the left eye, the ORs generally increased with higher MRD1 values in both eyes. This nonsignificant but directional trend implies a possible relationship between upper-eyelid position and dry eye symptoms. As shown in Figure 2, this upward trend was consistent across MRD1 categories in both eyes. DISCUSSION We used nationally representative health survey data to investigate the association between upper-eyelid position, measured by MRD1 values, and subjective dry eye symptoms. Higher MRD1 values were significantly associated with increased odds of experiencing self-reported dry eye symptoms. This finding aligns with previous research. For instance, Zloto et al. [8] reported that patients who underwent combined blepharoplasty and MMCR, but not upper blepharoplasty alone, experienced both subjective worsening and objective signs of dry eye. Because successful ptosis correction with MMCR typically results in increased MRD1, the authors suggested that an enlarged palpebral fissure may promote evaporative dry eye, and that reduced conjunctival secretory function might contribute to aqueous deficiency [8]. However, not all studies support this association. A recent study reported that MMCR did not lead to clinically meaningful changes in ocular surface parameters or postoperative dryness [13]. Similarly, Hamed Azzam et al. [11] found that levator aponeurosis advancement did not affect meibomian gland function or lead to worsening dry eye signs or symptoms. Notably, although we found a significant association between MRD1 values and subjective symptoms, MRD1 values were not associated with a clinical diagnosis of DED (Table S1 and S2). This implies that increased MRD1 may influence the perception of ocular discomfort without necessarily indicating measurable tear film instability. Indeed, objective dry eye tests often show weak correlations with dry eye symptoms and lack reproducibility [4, 14]. In thyroid eye disease, an increased interpalpebral fissure is associated with a decreased blink rate, incomplete eyelid closure, and greater corneal exposure, all of which may exacerbate ocular surface discomfort [15, 16]. Consistently, our study demonstrated that higher MRD1 values were associated with greater odds of reporting dry eye symptoms. In contrast, a study on aponeurogenic blepharoptosis also found that patients exhibited reduced Schirmer scores compared to age-matched controls [7], possibly reflecting a diminished reflex tearing response in ptosis patients. These findings highlight the complex interplay between eyelid anatomy, age-related changes, tear dynamics, and symptom perception. Patient-reported symptoms remain a critical component of dry eye diagnosis and management, particularly in the context of eyelid malposition or oculoplastic procedures. Our results emphasize the importance of considering patient-reported outcomes when evaluating the impact of eyelid position on ocular surface health. Future research should include both objective and subjective measures of dry eye, and assess other anatomical features—such as interpalpebral fissure width, eyelid curvature, and lash orientation—that may influence ocular surface stability. Longitudinal studies are warranted to determine whether changes in eyelid position precede the onset of symptoms or occur as a consequence. In line with previous studies on DED [17-25], our analysis found that dry eye symptoms were more prevalent among older individuals, women, and urban residents. Affected participants also had higher rates of hyperlipidaemia, thyroid disease, and prior ocular surgery, as well as shorter sleep duration and less sun exposure. These findings are in agreement with a previous population-based study that used the same KNHANES dataset [17]. In a population-based study of 4185 Koreans aged 65 years and older, the prevalence of dry eye symptoms was 17.9%. Multiple logistic regression analysis revealed that female sex, history of cataract, suicidal ideation, and hypercholesterolaemia were significantly associated with increased odds of experiencing symptoms, while being aged ≥ 80 years and sleeping ≥ 9 h per day were associated with reduced odds. These findings imply that both physical and psychosocial factors contribute to dry eye symptomatology in the elderly Korean population. This study had several limitations. First, its cross-sectional design limits causal inference; it remains unclear whether increased MRD1 precedes the development of symptoms or is a consequence. Second, dry eye was assessed using self-reported questionnaires rather than objective clinical tests such as the Schirmer test, tear breakup time, or fluorescein staining. Thus, our findings reflect perceived ocular discomfort rather than clinically confirmed DED. Despite these limitations, its strengths include the use of a large, nationally representative dataset and standardized ophthalmologic assessments. All measurements, including MRD1, were performed by trained ophthalmologists under the supervision of the Korea Disease Control and Prevention Agency and the Korean Ophthalmological Society, enhancing data reliability and generalizability. In conclusion, despite its limitations, this study provides meaningful insights into the relationship between upper-eyelid position and subjective dry eye symptoms in a Korean population aged 40 years and older, after adjusting for potential confounding factors. Clinicians should be aware of the potential for worsening dry eye symptoms following upper-eyelid surgeries, such as ptosis correction, and take this into account during preoperative assessment and patient counselling. Careful consideration of eyelid position may help to minimize postoperative ocular surface discomfort, particularly in patients with pre-existing ocular surface concerns. Declarations COMPETING INTERESTS The authors declare that they have no conflict of interest. FUNDING This work was also supported by the National Research Foundation of Korea Grant funded by the Korean Government (RS-2022-NR075626), and was partially supported by the Soonchunhyang University Research Fund. AUTHOR CONTRIBUTIONS YK was a major contributor to writing the manuscript. SH carried out the statistical analysis. SH and SYJ were responsible for the study conception and design, as well as the intellectual content of the paper. SCB critically revised the article and was involved in table design and data checking. All authors have read and agreed to the published version of the manuscript. References Uchino M, Schaumberg DA. Dry eye disease: impact on quality of life and vision. Curr Ophthalmol Rep. 2013;1:51–57. 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Demographic characteristics of the study subjects according to the presence or absence of dry eye symptoms. Dry eye symptoms P -value Absence ( n = 9421) Presence ( n = 1964) Age (years) 59.3 ± 11.3 60.3 ± 11.0 < 0.001 Gender < 0.001 Male 4318 (45.8) 555 (28.3) Female 5103 (54.2) 1409 (71.7) Area of residence (urban) 5892 (62.5) 1341 (68.3) < 0.001 Education 0.0018 ≤ Elementary school 3498 (37.1) 810 (41.2) Middle school graduate 1464 (15.5) 282 (14.4) High school graduate 2689 (28.5) 555 (28.3) ≥ College graduate 1770 (18.8) 317 (16.1) Household income 0.4418 Quartile 1 2419 (25.7) 524 (26.7) Quartile 2 2365 (25.1) 513 (26.1) Quartile 3 2205 (23.4) 444 (22.6) Quartile 4 2432 (25.8) 483 (24.6) Smoking status < 0.001 No 7678 (81.5) 1746 (88.9) Yes 1743 (18.5) 218 (11.1) Heavy drinker < 0.001 No 3249 (34.5) 789 (40.2) Yes (≤ 1 drinks/week) 2481 (26.3) 573 (29.2) Yes (2 drinks/month) 2829 (30.0) 492 (25.1) Yes (≥ 4 drinks/week) 862 (9.1) 110 (5.6) Body mass index (kg/m 2 ) 24.0 ± 3.2 24.0 ± 3.2 0.8962 Hypertension 3031 (32.2) 711 (36.2) < 0.001 Diabetes mellitus 1125 (11.9) 243 (12.4) 0.6195 Hypercholesterolaemia 1238 (13.1) 368 (18.7) < 0.001 History of ocular surgery 1380 (14.6) 457 (23.3) < 0.001 Rheumatoid arthritis 315 (3.3) 79 (4.0) 0.1529 History of depression 406 (4.3) 147 (7.5) < 0.001 Sun exposure (h/day) 0.0011 ≤ 2 5608 (59.5) 1238 (63.0) 2–5 2173 (23.1) 448 (22.8) ≥ 5 1640 (17.4) 278 (14.2) Duration of sleep (h) 6.7 ± 1.5 6.5 ± 1.5 < 0.001 Stress perception < 0.001 None 359 (3.8) 113 (5.8) Mild 1767 (18.8) 428 (21.8) Moderate 5339 (56.7) 1099 (56.0) Severe 1956 (20.8) 324 (16.5) Thyroid abnormality 407 (4.3) 149 (7.6) < 0.001 MRD1 right (mm) 0.0043 < 1.0 2775 (29.5) 508 (25.9) 1.0–1.9 3199 (34.0) 660 (33.6) 2.0–2.9 2106 (22.4) 485 (24.7) 3.0–3.9 995 (10.6) 222 (11.3) ≥ 4.0 346 (3.7) 89 (4.5) MRD1 left (mm) 0.0055 < 1.0 2768 (29.4) 503 (25.6) 1.0–1.9 3199 (34.0) 667 (34.0) 2.0–2.9 2108 (22.4) 480 (24.4) 3.0–3.9 991 (10.5) 236 (12.0) ≥ 4.0 355 (3.8) 78 (4.0) Values are n (%) or mean ± standard deviation. MRD1, marginal reflex distance 1. Table 2. Odds ratio and 95% confidence interval of association between MRD1 and dry eye symptoms. Adjusted OR Model 1 a Model 2 b Model 3 c OR 95% CI OR 95% CI OR 95% CI MRD1 right (mm) < 1.0 1 Reference 1 Reference 1 Reference 1.0–1.9 1.24* 1.03–1.50 1.24* 1.02–1.50 1.24* 1.02–1.50 2.0–2.9 1.27* 1.03–1.55 1.26* 1.01–1.56 1.28* 1.03–1.60 3.0–3.9 1.21 0.92–1.58 1.18 0.88–1.57 1.21 0.91–1.60 ≥ 4.0 1.70* 1.19–2.43 1.63* 1.10–2.42 1.65* 1.11–2.46 MRD1 left (mm) < 1.0 1 Reference 1 Reference 1 Reference 1.0–1.9 1.21* 1.00–1.46 1.20 0.98–1.45 1.19 0.98–1.45 2.0–2.9 1.28* 1.03–1.58 1.27* 1.02–1.60 1.31* 1.04–1.63 3.0–3.9 1.29* 1.00–1.66 1.25 0.95–1.64 1.28 0.97–1.68 ≥ 4.0 1.35 0.94–1.96 1.28 0.86–1.93 1.31 0.87–1.98 MRD1, marginal reflex distance 1; OR, odds ratio; CI, confidence interval. *P < 0.05. a Model 1: unadjusted. b Model 2: adjusted for age and sex. c Model 3: Model 2 + adjusted for area of residence, education level, body mass index, smoking, drinking, stress perception, sun exposure, income, hypertension, diabetes mellitus, depression, rheumatoid arthritis, hypercholesterolaemia, thyroid abnormality, duration of sleep, and history of ocular surgery. 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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-7015840","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":536419908,"identity":"f2c967ae-fc45-47cb-bd68-955f88c92f0e","order_by":0,"name":"Sun Young 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05:38:14","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":116298,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7015840/v1/d96dfd3ee036dcafd085e7d0.html"},{"id":95528565,"identity":"ba125ebc-d90e-400e-a047-d8e441eab962","added_by":"auto","created_at":"2025-11-10 10:16:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":604897,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart of inclusion and exclusion of the study subjects. KNHANES, Korea National Health and Nutrition Examination Survey.\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-7015840/v1/d463094c09f93e21599a9202.png"},{"id":95528620,"identity":"6530314b-439a-4acb-a800-3f5eeba83294","added_by":"auto","created_at":"2025-11-10 10:16:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":452496,"visible":true,"origin":"","legend":"\u003cp\u003eAdjusted odds ratios (ORs) for the incidence of dry eye symptoms across marginal reflex distance 1 (MRD1) categories in the right and left eyes. ORs are plotted with 95% confidence intervals. A trend toward increasing ORs with higher MRD1 values is observed in both eyes. The \u0026lt; 1-mm group serves as the reference (OR = 1.0); error bars represent 95% confidence intervals.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-7015840/v1/1229a5eba253a97cf5f75ab3.png"},{"id":101753776,"identity":"9f7473bc-a739-410e-b559-6a7791296639","added_by":"auto","created_at":"2026-02-03 10:40:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1809154,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7015840/v1/5a886d54-bdd1-4736-88b0-74ec2626df6f.pdf"},{"id":95502864,"identity":"c336babc-2950-42f7-a1db-afb118efedad","added_by":"auto","created_at":"2025-11-10 05:38:12","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":24294,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTables.docx","url":"https://assets-eu.researchsquare.com/files/rs-7015840/v1/69eb4723ab9b5e5e4355f752.docx"}],"financialInterests":"There is no conflict of interest","formattedTitle":"Association between dry eye symptoms and upper-eyelid position in Korean adults: A nationwide population-based study","fulltext":[{"header":"SUMMARY","content":"\u003cp\u003e\u003cstrong\u003eWhat was known before\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eDry eye disease (DED) is influenced by numerous factors such as age, sex, digital device use, and prior ocular surgery.\u003c/li\u003e\n \u003cli\u003eEyelid position may affect tear dynamics, but evidence linking marginal reflex distance 1 to dry eye symptoms is inconsistent.\u003c/li\u003e\n \u003cli\u003eObjective tests for DED are often poorly correlated with patient-reported symptoms.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhat this study adds\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eThis is the first population-based study to show a significant association between higher MRD1 values and self-reported dry eye symptoms.\u003c/li\u003e\n \u003cli\u003eThe findings highlight the role of eyelid position in symptom perception, independent of clinical DED diagnosis.\u003c/li\u003e\n \u003cli\u003eThe results emphasize the need to consider patient-reported outcomes when evaluating or planning eyelid surgery.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"INTRODUCTION","content":"\u003cp\u003eDry eye disease (DED) is a multifactorial disorder of the ocular surface characterized by disruption of tear film homeostasis, leading to ocular discomfort, visual disturbance, and reduced quality of life [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Well-established risk factors for DED include advanced age, female sex, digital device use, and a history of ocular surgery [\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In addition, recent studies have suggested that eyelid anatomy and function may also play roles in maintaining ocular surface stability.\u003c/p\u003e\u003cp\u003eIn particular, acquired aponeurogenic blepharoptosis is associated with altered tear dynamics and a higher prevalence of DED [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Patients with acquired blepharoptosis often demonstrate reduced tear production as measured by the Schirmer test [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, it remains unclear whether the decreased tear production contributes to the development of ptosis or simply reflects diminished reflex tearing secondary to the ptotic eyelid. Conversely, several clinical studies have reported changes in dry eye parameters following ptosis correction procedures, such as levator advancement or M\u0026uuml;ller muscle-conjunctival resection (MMCR), including changes in tear breakup time, corneal staining, and Schirmer test scores [\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Notably, long-term follow-up studies have shown that patients undergoing MMCR, but not those undergoing upper blepharoplasty, may experience a worsening of dry eye signs compared to their preoperative status [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAlthough the potential influence of eyelid position on ocular surface homeostasis is increasingly acknowledged, the findings remain inconsistent. It is still unclear whether eyelid position directly affects tear film stability or is associated simply through shared age-related factors. To the best of our knowledge, no previous study has quantitatively assessed the relationship between upper-eyelid position, commonly measured by marginal reflex distance 1 (MRD1), and subjective dry eye symptoms in a large-scale population-based setting.\u003c/p\u003e\u003cp\u003eTherefore, this study used a nationally representative health survey to investigate the association between MRD1\u0026mdash;as a surrogate marker of eyelid aperture\u0026mdash;and self-reported symptoms of dry eye.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e\u003cb\u003eStudy design and participants\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWe used data from the Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide, cross-sectional survey conducted by the Korea Centers for Disease Control and Prevention (KCDC) since 1998 [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The KNHANES collects comprehensive health-related data through interviews, self-administered questionnaires, physical examinations, and dietary assessments. It adopts a stratified, multistage probability sampling method based on household registries, with sampling stratified by geographic region, sex, and age. Each year, approximately 10,000 individuals are sampled from 192 primary sampling units, which are defined by administrative districts and housing characteristics. We focused on individuals aged 40 years and older who participated in the fifth KNHANES conducted from 2010 to 2012. Participants were excluded if they did not complete the ophthalmologic examination or failed to respond to key survey items used in this study.\u003c/p\u003e\u003cp\u003e\u003cb\u003eOphthalmologic examination\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOphthalmologic data were obtained through mobile examination units operated by board-certified ophthalmologists dispatched by the Korean Ophthalmological Society. Dry eye symptoms were evaluated based on self-reported responses. Participants were asked, \u0026ldquo;Have you ever experienced symptoms of dry eyes, such as a sensation of dryness or irritation?\u0026rdquo; Responses were recorded as either \u0026ldquo;yes\u0026rdquo; or \u0026ldquo;no,\u0026rdquo; and only self-reported symptom data were used in the analysis.\u003c/p\u003e\u003cp\u003eMRD1 was measured as the vertical distance from the corneal light reflex to the upper-eyelid margin in the primary gaze position, excluding the influence of dermatochalasis or brow ptosis. MRD1 values were categorized into five descending groups: \u0026lt; 1.0 mm, 1.0\u0026ndash;1.9 mm, 2.0\u0026ndash;2.9 mm, 3.0\u0026ndash;3.9 mm, and \u0026ge;\u0026thinsp;4.0 mm.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePotential mediators and confounders\u003c/b\u003e\u003c/p\u003e\u003cp\u003eData on demographic characteristics, socioeconomic indicators, medical history, and lifestyle behaviours were obtained through health interviews and physical examinations. Body mass index was calculated as weight in kilograms divided by height in meters squared (kg/m\u003csup\u003e2\u003c/sup\u003e). Participants were classified into two categories based on smoking status: current smokers and non-current smokers, the latter including both never and former smokers. Alcohol consumption was stratified into four groups: none, \u0026le; 1 drink per month, 2\u0026ndash;3 drinks per week, and \u0026ge;\u0026thinsp;4 drinks per week. Educational attainment was categorized into elementary school, middle school, high school, and college/university. Household income was divided into quartiles. Sleep duration was assessed by asking participants, \u0026ldquo;How many hours do you sleep each day?\u0026rdquo; Perceived stress was assessed using the question, \u0026ldquo;How stressed do you feel on a typical day?\u0026rdquo; Responses were categorized into four levels: none, mild (slightly stressed), moderate (moderately stressed), and severe (extremely stressed). Participants were also evaluated for the presence of comorbid conditions, including hypertension, diabetes mellitus, hypercholesterolaemia, rheumatoid arthritis, depression, history of ocular surgery, and thyroid disorders.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eCategorical variables were compared using the chi-square test, while continuous variables were analysed using independent samples \u003cem\u003et\u003c/em\u003e-tests. To estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs), logistic regression models were employed. We constructed three models to explore potential mediators and confounders. Model 1 was unadjusted. Model 2 was adjusted for age and sex. Model 3 was fully adjusted for age, sex, area of residence, education level, body mass index, smoking, drinking, stress perception, sun exposure, income, hypertension, diabetes mellitus, depression, rheumatoid arthritis, hypercholesterolaemia, thyroid abnormality, duration of sleep, and history of ocular surgery. Given the complex sampling design of the KNHANES dataset, all statistical analyses accounted for its multistage probability structure and incorporated survey weights to ensure nationally representative estimates. All analyses were performed using IBM SPSS Statistics for Windows, version 26.0 (IBM Corp., Armonk, NY, USA) and Python (version 3.12). A two-sided \u003cem\u003eP\u003c/em\u003e-value of less than 0.05 was considered to indicate statistical significance.\u003c/p\u003e\u003cp\u003e\u003cb\u003eEthics statement\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe Institutional Review Board of the Korea Centers for Disease Control and Prevention approved the KNHANES V (approval no. 2010-02CON-21-C), and all participants provided informed consent. The study followed the principles of the Declaration of Helsinki and complied with all relevant guidelines and regulations.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eIn all, 24,173 individuals participated in the KNHANES from 2010 to 2012. After excluding participants under 40 years of age (n = 10,919), 13,254 individuals remained. Among them, 1031 individuals who did not undergo ophthalmologic examination were excluded, resulting in 12,223 participants. Subsequently, 838 individuals with incomplete data were further excluded. The final analysis included 11,385 participants (Fig. 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBaseline characteristics according to dry eye symptoms\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong the 11,385 participants, 1964 individuals (17.3%) reported having dry eye symptoms, while 9421 (82.7%) did not. Table 1 presents the baseline characteristics according to dry eye symptom status. Participants with symptoms were significantly (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001) more likely to be female (71.7% vs. 54.2%), older (60.3 ± 11.0 years vs. 59.3 ± 11.3 years), to reside in an urban area (68.3% vs. 62.5%), and to have thyroid abnormalities (7.6% vs. 4.3%), hypercholesterolaemia (18.7% vs. 13.1%), a history of ocular surgery (23.3% vs. 14.6%), shorter mean sleep duration (6.5 ± 1.5 h vs. 6.7 ± 1.5 h), and less perceived stress. Sun exposure times also differed significantly between the groups: 63.0% of individuals with symptoms reported being exposed to sunlight for ≤ 2 h per day compared to 59.5% in the asymptomatic group; the values were 14.2% and 17.4%, respectively, for ≥ 5 h sun exposure.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;The distribution of MRD1 values also differed significantly between the groups. In the right eye, 25.9% of participants with symptoms had an MRD1 value of less than 1 mm compared to 29.5% of those without symptoms, and 4.5% of individuals with symptoms had an MRD1 value ≥ 4 mm compared to 3.7% of the non-dry eye group. Similar differences were observed in the left eye, with 25.6% in the dry eye group having an MRD1 value \u0026lt; 1 mm vs. 29.4% in the control group, and 4.0% vs. 3.8%, respectively, having an MRD1 value ≥ 4 mm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRelationship between upper-eyelid position and dry eye symptoms\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe association between MRD1 values and the presence of dry eye symptoms is summarized in Table 2 and illustrated in Figure 2. In the unadjusted and partially adjusted models (Models 1 and 2), increasing MRD1 values in both eyes were associated with higher odds of symptoms. This trend persisted after full adjustment for multiple demographic, behavioural, and clinical covariates in Model 3.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;In the fully adjusted model, individuals with right eye MRD1 values of 1–1.9 mm and 2–2.9 mm had significantly increased odds of symptoms compared to those with MRD1 values of \u0026lt; 1 mm, with ORs of 1.24 and 1.28, respectively (see the table for CI values). Participants in the highest MRD1 category (≥ 4 mm) also had an elevated OR (OR = 1.65). In the left eye, a significant association was found only in the 2–2.9 mm group (OR = 1.31).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Although not all categories reached statistical significance, particularly in the left eye, the ORs generally increased with higher MRD1 values in both eyes. This nonsignificant but directional trend implies a possible relationship between upper-eyelid position and dry eye symptoms. As shown in Figure 2, this upward trend was consistent across MRD1 categories in both eyes.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eWe used nationally representative health survey data to investigate the association between upper-eyelid position, measured by MRD1 values, and subjective dry eye symptoms. Higher MRD1 values were significantly associated with increased odds of experiencing self-reported dry eye symptoms. This finding aligns with previous research. For instance, Zloto et al.\u0026nbsp;[8] reported that patients who underwent combined blepharoplasty and MMCR, but not upper blepharoplasty alone, experienced both subjective worsening and objective signs of dry eye. Because successful ptosis correction with MMCR typically results in increased MRD1, the authors suggested that an enlarged palpebral fissure may promote evaporative dry eye, and that reduced conjunctival secretory function might contribute to aqueous deficiency [8].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, not all studies support this association. A recent study reported that MMCR did not lead to clinically meaningful changes in ocular surface parameters or postoperative dryness [13]. Similarly, Hamed Azzam et al.\u0026nbsp;[11] found that levator aponeurosis advancement did not affect meibomian gland function or lead to worsening dry eye signs or symptoms. Notably, although we found a significant association between MRD1 values and subjective symptoms, MRD1 values were not associated with a clinical diagnosis of DED (Table S1 and S2). This implies that increased MRD1 may influence the perception of ocular discomfort without necessarily indicating measurable tear film instability. Indeed, objective dry eye tests often show weak correlations with dry eye symptoms and lack reproducibility [4, 14]. In thyroid eye disease, an increased interpalpebral fissure is associated with a decreased blink rate, incomplete eyelid closure, and greater corneal exposure, all of which may exacerbate ocular surface discomfort [15, 16]. Consistently, our study demonstrated that higher MRD1 values were associated with greater odds of reporting dry eye symptoms. In contrast, a study on aponeurogenic blepharoptosis also found that patients exhibited reduced Schirmer scores compared to age-matched controls\u0026nbsp;[7], possibly reflecting a diminished reflex tearing response in ptosis patients. These findings highlight the complex interplay between eyelid anatomy, age-related changes, tear dynamics, and symptom perception.\u003c/p\u003e\n\u003cp\u003ePatient-reported symptoms remain a critical component of dry eye diagnosis and management, particularly in the context of eyelid malposition or oculoplastic procedures. Our results emphasize the importance of considering patient-reported outcomes when evaluating the impact of eyelid position on ocular surface health. Future research should include both objective and subjective measures of dry eye, and assess other anatomical features—such as interpalpebral fissure width, eyelid curvature, and lash orientation—that may influence ocular surface stability. Longitudinal studies are warranted to determine whether changes in eyelid position precede the onset of symptoms or occur as a consequence.\u003c/p\u003e\n\u003cp\u003eIn line with previous studies on DED [17-25], our analysis found that dry eye symptoms were more prevalent among older individuals, women, and urban residents. Affected participants also had higher rates of hyperlipidaemia, thyroid disease, and prior ocular surgery, as well as shorter sleep duration and less sun exposure. These findings are in agreement with a previous population-based study that used the same KNHANES dataset [17]. In a population-based study of 4185 Koreans aged 65 years and older, the prevalence of dry eye symptoms was 17.9%. Multiple logistic regression analysis revealed that female sex, history of cataract, suicidal ideation, and hypercholesterolaemia were significantly associated with increased odds of experiencing symptoms, while being aged ≥ 80 years and sleeping ≥ 9 h per day were associated with reduced odds. These findings imply that both physical and psychosocial factors contribute to dry eye symptomatology in the elderly Korean population.\u003c/p\u003e\n\u003cp\u003eThis study had several limitations. First, its cross-sectional design limits causal inference; it remains unclear whether increased MRD1 precedes the development of symptoms or is a consequence. Second, dry eye was assessed using self-reported questionnaires rather than objective clinical tests such as the Schirmer test, tear breakup time, or fluorescein staining. Thus, our findings reflect perceived ocular discomfort rather than clinically confirmed DED. Despite these limitations, its strengths include the use of a large, nationally representative dataset and standardized ophthalmologic assessments. All measurements, including MRD1, were performed by trained ophthalmologists under the supervision of the Korea Disease Control and Prevention Agency and the Korean Ophthalmological Society, enhancing data reliability and generalizability.\u003c/p\u003e\n\u003cp\u003eIn conclusion, despite its limitations, this study provides meaningful insights into the relationship between upper-eyelid position and subjective dry eye symptoms in a Korean population aged 40 years and older, after adjusting for potential confounding factors. Clinicians should be aware of the potential for worsening dry eye symptoms following upper-eyelid surgeries, such as ptosis correction, and take this into account during preoperative assessment and patient counselling. Careful consideration of eyelid position may help to minimize postoperative ocular surface discomfort, particularly in patients with pre-existing ocular surface concerns.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eCOMPETING INTERESTS\u003c/h2\u003e\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFUNDING\u003c/h2\u003e\u003cp\u003eThis work was also supported by the National Research Foundation of Korea Grant funded by the Korean Government (RS-2022-NR075626), and was partially supported by the Soonchunhyang University Research Fund.\u003c/p\u003e\u003ch2\u003eAUTHOR CONTRIBUTIONS\u003c/h2\u003e\u003cp\u003eYK was a major contributor to writing the manuscript. SH carried out the statistical analysis. SH and SYJ were responsible for the study conception and design, as well as the intellectual content of the paper. SCB critically revised the article and was involved in table design and data checking. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eUchino M, Schaumberg DA. Dry eye disease: impact on quality of life and vision. Curr Ophthalmol Rep.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2013;1:51\u0026ndash;57.\u003c/li\u003e\n \u003cli\u003eCraig JP, Nelson JD, Azar DT, Belmonte C, Bron AJ, Chauhan SK, et al. TFOS DEWS II Report Executive Summary. Ocul Surf.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2017;15:802\u0026ndash;812.\u003c/li\u003e\n \u003cli\u003eGayton JL. Etiology, prevalence, and treatment of dry eye disease. Clin Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2009;3:405\u0026ndash;412.\u003c/li\u003e\n \u003cli\u003eEpidemiology DEWS Subcommittee. The epidemiology of dry eye disease: report of the Epidemiology Subcommittee of the International Dry Eye WorkShop (2007). Ocul Surf.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2007;5:93\u0026ndash;107.\u003c/li\u003e\n \u003cli\u003eAhn JM, Lee SH, Rim TH, Park RJ, Yang HS, Kim TI, et al. Prevalence of and risk factors associated with dry eye: the Korea National Health and Nutrition Examination Survey 2010\u0026ndash;2011. Am J Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2014;158:1205\u0026ndash;1214.e1207.\u003c/li\u003e\n \u003cli\u003eAyaki M, Kawashima M, Negishi K, Kishimoto T, Mimura M, Tsubota K. Sleep and mood disorders in women with dry eye disease. Sci Rep.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2016;6:35276.\u003c/li\u003e\n \u003cli\u003eMoesen I, van den Bosch W, Wubbels R, Paridaens D. Is dry eye associated with acquired aponeurogenic blepharoptosis? Orbit.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2014;33:173\u0026ndash;177.\u003c/li\u003e\n \u003cli\u003eZloto O, Matani A, Prat D, Leshno A, Ben Simon G. The effect of a ptosis procedure compared to an upper blepharoplasty on dry eye syndrome. Am J Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2020;212:1\u0026ndash;6.\u003c/li\u003e\n \u003cli\u003eLeatherbarrow B, Saha K. Complications of blepharoplasty. Facial Plast Surg.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2013;29:281\u0026ndash;288.\u003c/li\u003e\n \u003cli\u003eZloto O, Alcalay I, Klain B, Ben Simon G. The long-term effect on dry eye of posterior approach ptosis surgery vs. upper eyelid blepharoplasty. Curr Eye Res.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2024;49:538\u0026ndash;542.\u003c/li\u003e\n \u003cli\u003eHamed Azzam S, Nama A, Hartstein M, Habib HJ, Mukari A. The effect of ptosis surgery on meibomian glands and dry eye syndrome. Ophthalmic Plast Reconstr Surg.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2024;40:174\u0026ndash;177.\u003c/li\u003e\n \u003cli\u003eKweon S, Kim Y, Jang MJ, Kim Y, Kim K, Choi S, et al. Data resource profile: the Korea National Health and Nutrition Examination Survey (KNHANES). Int J Epidemiol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2014;43:69\u0026ndash;77.\u003c/li\u003e\n \u003cli\u003eBautista SA, Wladis EJ, Schultze RL. Quantitative assessment of dry eye parameters after M\u0026uuml;ller\u0026rsquo;s muscle-conjunctival resection. Ophthalmic Plast Reconstr Surg.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2018;34:562\u0026ndash;564.\u003c/li\u003e\n \u003cli\u003eNichols KK, Nichols JJ, Mitchell GL. The lack of association between signs and symptoms in patients with dry eye disease. Cornea.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2004;23:762\u0026ndash;770.\u003c/li\u003e\n \u003cli\u003eBrasil MV, Brasil OF, Vieira RP, Vaisman M, Amaral Filho OM. Tear film analysis and its relation with palpebral fissure height and exophthalmos in Graves\u0026rsquo; ophthalmopathy. Arq Bras Oftalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2005;68:615\u0026ndash;618.\u003c/li\u003e\n \u003cli\u003eAllam IY, Lazreg S, Shafik Shaheen M, Doheim MF, Mohammed MA. Ocular surface changes in patients with thyroid eye disease: an observational clinical study. Clin Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2021;15:2481\u0026ndash;2488.\u003c/li\u003e\n \u003cli\u003eKim KI, Park YS, Kim RH, Kim JH. Factors associated with dry eye symptoms in elderly Koreans: the Fifth Korea National Health and Nutrition Examination Survey 2010\u0026ndash;2012. Korean J Fam Med.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2019;40:22\u0026ndash;30.\u003c/li\u003e\n \u003cli\u003eSchein OD, Mu\u0026ntilde;oz B, Tielsch JM, Bandeen-Roche K, West S. Prevalence of dry eye among the elderly. Am J Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e1997;124:723\u0026ndash;728.\u003c/li\u003e\n \u003cli\u003eMoss SE, Klein R, Klein BE. Prevalence of and risk factors for dry eye syndrome. Arch Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2000;118:1264\u0026ndash;1268.\u003c/li\u003e\n \u003cli\u003eShimmura S, Shimazaki J, Tsubota K. Results of a population-based questionnaire on the symptoms and lifestyles associated with dry eye. Cornea.\u003cem\u003e\u0026nbsp;\u003c/em\u003e1999;18:408\u0026ndash;411.\u003c/li\u003e\n \u003cli\u003eChia EM, Mitchell P, Rochtchina E, Lee AJ, Maroun R, Wang JJ. Prevalence and associations of dry eye syndrome in an older population: the Blue Mountains Eye Study. Clin Exp Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2003;31:229\u0026ndash;232.\u003c/li\u003e\n \u003cli\u003eLee AJ, Lee J, Saw SM, Gazzard G, Koh D, Widjaja D, et al. Prevalence and risk factors associated with dry eye symptoms: a population-based study in Indonesia. Br J Ophthalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2002;86:1347\u0026ndash;1351.\u003c/li\u003e\n \u003cli\u003eBritten-Jones AC, Wang MTM, Samuels I, Jennings C, Stapleton F, Craig JP. Epidemiology and risk factors of dry eye disease: considerations for clinical management. Medicina (Kaunas).\u003cem\u003e\u0026nbsp;\u003c/em\u003e2024;60.\u003c/li\u003e\n \u003cli\u003eQian L, Wei W. Identified risk factors for dry eye syndrome: a systematic review and meta-analysis. PLoS One.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2022;17:e0271267.\u003c/li\u003e\n \u003cli\u003eZemanov\u0026aacute; M. Dry eye disease: a review. Cesk Slov Oftalmol.\u003cem\u003e\u0026nbsp;\u003c/em\u003e2021;77:107\u0026ndash;119.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Demographic characteristics of the study subjects according to the presence or absence of dry eye symptoms.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 331px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDry eye symptoms\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbsence (\u003cem\u003en\u003c/em\u003e = 9421)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePresence (\u003cem\u003en\u003c/em\u003e = 1964)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e59.3 \u0026plusmn; 11.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e60.3 \u0026plusmn; 11.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e4318 (45.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e555 (28.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e5103 (54.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1409 (71.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eArea of residence (urban)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e5892 (62.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1341 (68.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eEducation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.0018\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026le; Elementary school\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e3498 (37.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e810 (41.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eMiddle school graduate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1464 (15.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e282 (14.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHigh school graduate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2689 (28.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e555 (28.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026ge; College graduate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1770 (18.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e317 (16.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHousehold income\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.4418\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eQuartile 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2419 (25.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e524 (26.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eQuartile 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2365 (25.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e513 (26.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eQuartile 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2205 (23.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e444 (22.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eQuartile 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2432 (25.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e483 (24.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eSmoking status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e7678 (81.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1746 (88.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1743 (18.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e218 (11.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHeavy drinker\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e3249 (34.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e789 (40.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eYes (\u0026le; 1 drinks/week)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2481 (26.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e573 (29.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eYes (2 drinks/month)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2829 (30.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e492 (25.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eYes (\u0026ge; 4 drinks/week)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e862 (9.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e110 (5.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eBody mass index (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e24.0 \u0026plusmn; 3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e24.0 \u0026plusmn; 3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.8962\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHypertension\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e3031 (32.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e711 (36.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eDiabetes mellitus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1125 (11.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e243 (12.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.6195\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHypercholesterolaemia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1238 (13.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e368 (18.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHistory of ocular surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1380 (14.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e457 (23.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eRheumatoid arthritis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e315 (3.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e79 (4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.1529\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eHistory of depression\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e406 (4.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e147 (7.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eSun exposure (h/day)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.0011\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026le; 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e5608 (59.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1238 (63.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e2\u0026ndash;5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2173 (23.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e448 (22.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026ge; 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1640 (17.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e278 (14.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eDuration of sleep (h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e6.7 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e6.5 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eStress perception\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e359 (3.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e113 (5.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eMild\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1767 (18.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e428 (21.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eModerate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e5339 (56.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1099 (56.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eSevere\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e1956 (20.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e324 (16.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eThyroid abnormality\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e407 (4.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e149 (7.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eMRD1 right (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.0043\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026lt; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2775 (29.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e508 (25.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e1.0\u0026ndash;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e3199 (34.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e660 (33.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e2.0\u0026ndash;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2106 (22.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e485 (24.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e3.0\u0026ndash;3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e995 (10.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e222 (11.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026ge; 4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e346 (3.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e89 (4.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003eMRD1 left (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e0.0055\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026lt; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2768 (29.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e503 (25.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e1.0\u0026ndash;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e3199 (34.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e667 (34.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e2.0\u0026ndash;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e2108 (22.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e480 (24.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e3.0\u0026ndash;3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e991 (10.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e236 (12.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026ge; 4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e355 (3.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 165px;\"\u003e\n \u003cp\u003e78 (4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eValues are n (%) or mean \u0026plusmn; standard deviation.\u0026nbsp;MRD1, marginal reflex distance 1.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Odds ratio and 95% confidence interval of association between MRD1 and dry eye symptoms.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" style=\"width: 74px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAdjusted OR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eModel 1\u003csup\u003ea\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eModel 2\u003csup\u003eb\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 24px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eModel 3\u003csup\u003ec\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003eMRD1 right (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026lt; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e1.0\u0026ndash;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.24*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.03\u0026ndash;1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.24*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.02\u0026ndash;1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.24*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e1.02\u0026ndash;1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e2.0\u0026ndash;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.27*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.03\u0026ndash;1.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.26*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.01\u0026ndash;1.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.28*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e1.03\u0026ndash;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e3.0\u0026ndash;3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.92\u0026ndash;1.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.88\u0026ndash;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e0.91\u0026ndash;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026ge; 4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.70*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.19\u0026ndash;2.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.63*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.10\u0026ndash;2.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.65*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e1.11\u0026ndash;2.46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003eMRD1 left (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026lt; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e1.0\u0026ndash;1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.21*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.00\u0026ndash;1.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.98\u0026ndash;1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e0.98\u0026ndash;1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e2.0\u0026ndash;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.28*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.03\u0026ndash;1.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.27*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.02\u0026ndash;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.31*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e1.04\u0026ndash;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e3.0\u0026ndash;3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.29*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e1.00\u0026ndash;1.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.95\u0026ndash;1.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e0.97\u0026ndash;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026ge; 4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.94\u0026ndash;1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0.86\u0026ndash;1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e0.87\u0026ndash;1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMRD1, marginal reflex distance 1; OR, odds ratio; CI, confidence interval. *P \u0026lt; 0.05. \u003csup\u003ea\u003c/sup\u003eModel 1: unadjusted.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003eb\u003c/sup\u003eModel 2: adjusted for age and sex. \u003csup\u003ec\u003c/sup\u003eModel 3: Model 2 + adjusted for area of residence, education level, body mass index, smoking, drinking, stress perception, sun exposure, income, hypertension, diabetes mellitus, depression, rheumatoid arthritis, hypercholesterolaemia, thyroid abnormality, duration of sleep, and history of ocular surgery.\u003c/p\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":"","lastPublishedDoi":"10.21203/rs.3.rs-7015840/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7015840/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBACKGROUND\u003c/h2\u003e\u003cp\u003eTo investigate the association between dry eye symptoms and upper-eyelid position in a nationally representative Korean population.\u003c/p\u003e\u003ch2\u003eMETHODS\u003c/h2\u003e\u003cp\u003eData from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted between 2010 and 2012 were analysed to assess the relationship between upper-eyelid position and the presence of dry eye symptoms. In total, 11,385 subjects aged 40 years or older were included, and multiple logistic regression was performed to adjust for potential confounders. Sampling weights were applied to obtain estimates for the general Korean population.\u003c/p\u003e\u003ch2\u003eRESULTS\u003c/h2\u003e\u003cp\u003ePatients with dry eye symptoms were more likely to be women, non-smokers, and non-drinkers, and were more commonly residents of urban areas. They also had elevated marginal reflex distance 1 (MRD1) values and a higher prevalence of hypertension, depressive disorder, hyperlipidaemia, and thyroid diseases. An increase in MRD1 was significantly associated with higher odds of experiencing dry eye symptoms in both the right and left eyes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0043 and \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0055, respectively).\u003c/p\u003e\u003ch2\u003eCONCLUSIONS\u003c/h2\u003e\u003cp\u003eIncreased MRD1 was significantly associated with dry eye symptoms in a representative Korean population. These findings imply that dry eye symptoms can potentially worsen after upper-eyelid surgeries, including ptosis correction, and should be considered during preoperative evaluation and counselling.\u003c/p\u003e","manuscriptTitle":"Association between dry eye symptoms and upper-eyelid position in Korean adults: A nationwide population-based study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-10 05:38:07","doi":"10.21203/rs.3.rs-7015840/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":"8f2ad39e-881f-417a-8bf6-6c53ca3fceb2","owner":[],"postedDate":"November 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":57036462,"name":"Health sciences/Signs and symptoms/Eye manifestations"},{"id":57036463,"name":"Health sciences/Risk factors"},{"id":57036464,"name":"Health sciences/Medical research/Epidemiology"}],"tags":[],"updatedAt":"2026-02-02T17:56:53+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-10 05:38:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7015840","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7015840","identity":"rs-7015840","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}