Adaptive Changes in Pupil and Iris Morphology in Multi-ethnic Populations Exposed to High-Intensity Light in Luntai, Xinjiang

Adaptive Changes in Pupil and Iris Morphology in Multi-ethnic Populations Exposed to High-Intensity Light in Luntai, Xinjiang | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Adaptive Changes in Pupil and Iris Morphology in Multi-ethnic Populations Exposed to High-Intensity Light in Luntai, Xinjiang Haiting Chen, Guifang Fang, Chunmin Zhao, Gulijiemilai Aierken This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9410208/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Objective To assess pupillary and iris structural differences between Uyghur and Han populations with different residence durations in southern Xinjiang. Methods In this cross-sectional study, 80 healthy adults (160 eyes) were grouped by ethnicity and residence duration. Pupil metrics were obtained using smartphone video analysis; iris thickness was measured by anterior segment OCT. Questionnaire data on light exposure and protection were collected. Statistical analyses included ANOVA, nonparametric tests, and linear regression. Results There were no significant differences in demographic characteristics among the four groups. The Uyghur group had smallest pupil diameters and most reduced constriction amplitudes. With the extension of residence time, the pupil diameters of the Han population showed a gradient decrease (short-term > new migration > long-term), and the contraction amplitudes decreased simultaneously. The iris thickness of the Uyghur group was greater than that of the Han group,while the iris thickness of the long-term resident Han group was significantly thicker than that of the newly migrated and short-term groups. Outdoor exposure negatively correlated with pupil diameter but not with iris thickness. Conclusion Prolonged light exposure in Xinjiang may lead to pupillary constriction and iris thickening, showing ethnic and duration-dependent adaptations. Pupil Tomography Optical Coherence Ethnicity Environmental Exposure Preface Research on the impact mechanisms of lighting environments on the human visual system is a crucial topic in the field of environmental health. Studies have shown that populations in plateau regions commonly exhibit physiological adaptive changes such as pupil constriction and iris thickening [ 1 ]. However, for areas with lower altitudes but strong light characteristics, such as Xinjiang, China (annual average ultraviolet index UVI > 8, sunshine duration exceeding 2800 hours) [ 2 ], such adaptive-related research remains relatively scarce. Xinjiang possesses unique climatic and geographical features, including moderate latitude, arid climate, and high atmospheric transparency, which result in ultraviolet radiation intensity similar to that of high-altitude regions with thin air [ 3 ]. This provides ideal conditions for studying the effects of pure strong light on the human visual system. With regional socioeconomic development, environmental adaptability research has become a critical interdisciplinary topic spanning anthropology, medicine, and visual sciences. This study employs optical coherence tomography (OCT) technology [ 4 ] to non-invasively quantify iris structural characteristics across diverse populations, combined with standardized pupil measurements, to investigate the impact of long-term environmental adaptation on visual physiological functions. These findings not only enhance our understanding of human biodiversity but also hold significant practical implications for regional public health policy formulation and clinical ophthalmic diagnosis and treatment. 1 Materials and Methods 1.1 General Information This study was conducted from January 2025 to December 2025 at the Ophthalmology Outpatient Department of LunTai County People's Hospital in Xinjiang. Healthy adults aged 18–60 years were involved and divided into four groups based on continuous residence time and ethnicity: local Uyghur residents(continuous residence > 18 years), long-term (continuous residence > 15 years), medium-term (continuous residence 2–5 years), and short-term Han Chinese residents (continuous residence < 3 months). All participants underwent detailed ophthalmological examinations and systemic health assessments to exclude ocular diseases such as glaucoma and optic neuropathy, as well as systemic diseases affecting pupil size (e.g., diabetes and cerebrovascular diseases) and long-term medication history. The study adhered to the principles of the Helsinki Declaration and was approved by the hospital ethics committee (Luntai County People's Hospital Ethics Approval No.2025.4). All participants signed informed consent forms. The sample size was calculated with α = 0.05 and β = 0.1. 1.2 Research Methods This study adopted a cross-sectional research design, using standardized questionnaires to collect demographic characteristics, residential and occupational exposure histories, protective measures, and other information from participants: such as continuous residence time in Luntai; occupational types including indoor office work, mixed indoor-outdoor work, and outdoor work; average daily outdoor activity time; frequency of sunglasses use; ocular discomfort or diseases, etc. All participants underwent systematic eye examinations: visual acuity testing used a logarithmic visual acuity chart compliant with GB 11533 − 2011 standards, and anterior segment examination employed a Lanling KJ5E slit lamp microscope. Pupillary diameters were measured using smartphone video analysis: all measurements were conducted in a dark room with constant lighting (illuminance < 5 lux). Participants were required to adapt to the dark environment for at least 10 minutes to ensure stable pupil size, fixing their gaze on distant targets while avoiding near-vision activities requiring accommodation and convergence, such as reading or using mobile phones. Participants sat with their corneas 30 cm from the lens, looking straight at the phone screen. The LED light source (100 lux) automatically activated at frame 10 of the video (lasting 5 seconds) and recorded continuously for 10 seconds (1 second before stimulation + 4 seconds after stimulation). Measurements were repeated three times with 2-minute intervals, recording pupillary diameters under illumination conditions to calculate the constriction amplitude. Iris thickness measurements were performed using the YG-100K SE Ophthalmic Optical Coherence Tomography Scanner. Imaging was conducted with a preset volumetric scanning protocol comprising 128 radial scans, each with a length of 16 mm and depth of 6 mm, at scanning angles ranging from 0°to 180° (with 45°intervals). The total iris thickness was determined by selecting the thickest section from four sectors (nasal, temporal, superior, and inferior) and calculating the average value [ 5 ]. To ensure data quality, all equipment underwent daily calibration. The examinations were performed by two trained technicians using a dual-independent data entry method. 1.3 Statistical Methods Statistical analysis was performed using SPSS 19.0 software. Age, outdoor activity duration, pupil diameter, constriction amplitude, and iris thickness were measured as continuous variables, expressed as mean ± standard deviation. Normality and homogeneity of variance were assessed using one-way ANOVA. For continuous variables that met the normal distribution and homogeneity of variance criteria, between-group comparisons were conducted using independent samples t-test; multi-group comparisons employed one-way ANOVA, with post-hoc pairwise comparisons performed using Tukey test. For continuous variables that did not meet normal distribution or homogeneity of variance criteria, nonparametric tests (Kruskal-Wallis test) were applied to assess intergroup differences, followed by Mann-Whitney U test for pairwise comparisons. Gender and sunglasses usage frequency were categorical variables analyzed using chi-square test for differences and Mann-Whitney U test for pairwise comparisons. For correlations between two continuous variables, Pearson correlation analysis was used if both variables followed normal distribution; if one or more variables deviated from normal distribution, Spearman rank correlation analysis was employed. A P-value < 0.05 was considered statistically significant. 2. Results 2.1 Basic Characteristics of Study Subjects The study ultimately included 80 subjects with a total of 160 eyes, among whom 50 were male (62.5%) and 30 were female (37.5%). They were divided into four groups based on ethnicity and duration of residence, as shown in Table 1 : The local Uyghur residents group (continuous residence > 18 years) consisted of 40 individuals (24 males and 16 females), with an average age of (48.9 ± 20.6) years; the long-term Han Chinese group comprised 40 individuals (continuous residence > 15 years) (28 males and 12 females), with an average age of (58.5 ± 19.7) years; the medium-term Han Chinese group included 40 individuals (continuous residence 2–5 years) (22 males and 18 females), with an average age of (55.2 ± 18.4) years; and short-term Han Chinese residents group (continuous residence < 3 months) consisted of 40 individuals (26 males and 16 females), with an average age of (53.1 ± 16.4) years. There were no statistically significant differences in age (F = 4.913, p = 0.178) or gender composition (χ²=2.133, p = 0.545) among the four groups. Table 1 General characteristics of study subjects Gender(Male /Female) Local Uyghur residents Long-term Han Chinese residents Medium-term Han Chinese residents Short-term Han Chinese residents P 24/16 28/12 22/18 26/16 0.545 Age(year) 48.9 ± 20.6 58.5 ± 19.7 55.2 ± 18.4 53.1 ± 16.4 0.178 2.2 Pupillary Adaptation Changes Under Intense Light Conditions As shown in Table 2 , under darkroom and standard bright light conditions, the pupillary diameters of Uyghur residents was generally smaller than that of long-term Han Chinese residents. Long-term Han Chinese residents (> 15 years) exhibited smaller pupillary diameters compared to medium-term group (2–5 years) who had smaller pupillary diameters than short-term residents (< 3 months). The Uyghur resident group demonstrated the smallest baseline pupillary diameters, with significantly lower contraction amplitudes under light stimulation compared to long-term Han Chinese residents. The pupillary contraction amplitudes increased sequentially among long-term Han Chinese residents, medium-term Han Chinese residents, and short-term Han Chinese residents, with statistically significant differences. This indicates that smaller baseline pupillary diameters had relatively limited contraction spaces, whereas larger pupillary diameters exhibit greater contraction amplitudes under light stimulation. 2.3 Imaging characteristics of iris structures As shown in Table 2 , anterior segment OCT measurements revealed that the average iris thicknesses were greater in Uyghur residents compared to Han Chinese residents. Among Han Chinese residents, long-term residents exhibited significantly thicker iris stroma layers than medium-term or short-term residents, with statistically significant differences. Although medium-term Han Chinese resident showed slightly increased average iris thicknesses compared to short-term residents, the difference was not statistically significant. Table 2 Biological parameters of anterior segment in populations of different ethnicities and residence durations Local Uyghur residents Long-term Han Chinese residents Medium-term Han Chinese residents Short-term Han Chinese residents Test Pupillary diameter (dark) (mm) 2.47 ± 0.23 3.14 ± 0.52 3.88 ± 0.51 4.63 ± 0.56 χ 2 = 120.487 P = 0.000 Group comparison (Z-score) - -5.615** -7.699** -7.699** - - -5.168** -7.347** - - - -5.206** Pupillary diameter (light) (mm) 1.86 ± 0.27 2.18 ± 0.35 2.62 ± 0.47 2.88 ± 0.53 χ 2 = 85.573 P = 0.000 Group comparison (Z-score) - -4.013** -6.919** -7.289** - - -4.230** -5.707** - - - -2.377* Compression amplitude (mm) 0.61 ± 0.21 0.97 ± 0.31 1.26 ± 0.29 1.76 ± 0.51 χ 2 = 104.859 P = 0.000 Group comparison (Z-score) - -5.390** -7.266** -7.699** - - -4.279** -6.419** - - - -4.283** Iris thickness (um) 450.5 ± 51.3 407.7 ± 39.6 369.6 ± 59.7 346.9 ± 64.5 F = 31.132 P = 0.000 Group comparison (P-score) - 0.002 0.000 0.000 - - 0.006 0.000 - - - 0.205 *: P <0.05 **༚ P <0.001 2.4 Modifying Effects of Sunlight Exposure Prolonged outdoor activity duration was associated with smaller pupil diameters (r=-0.352, r=-0.258) and reduced constriction amplitudes (r=-0.370) in darkroom and bright light conditions, respectively. However, the positive correlation with increased iris thicknesses (r = 0.134) was not statistically significant. Other factors such as gender, age, and sunglasses usage showed no significant correlation with pupil or iris thickness (Table 3 ). Table 3 Correlation between factors and biological parameters of the anterior segments Pupillary diameter (dark) (mm) Gender Age Outdoor time Sunglasses 0.824 0.280 0.000* 0.609 Pupillary diameter (light) (mm) 0.652 0.641 0.001* 0.472 Compression amplitude (mm) 0.685 0.516 0.000* 0.943 Iris thickness (um) 0.437 0.578 0.090 0.843 *: P <0.05 3. Discussion This study explored the ocular parameter characteristics of different populations (local Uyghurs, long-term Han residents, medium-term Han residents, and short-term residents) in Luntai, Bayingolin Mongolian Autonomous Prefecture, Xinjiang, through a cross-sectional design. The indicators included pupil diameter, pupillary constriction amplitude, and iris thickness, demonstrating the effects of ethnic groups and residence duration on ocular physiological features. It also suggested potential adaptive changes in the eyes under high ultraviolet radiation environments. This study found that the Uyghur population exhibited characteristics of smaller pupil diameters, reduced constriction amplitudes, and increased iris thicknesses compared to Han residents. In contrast, Han populations showed adaptive reduction in pupil diameters with prolonged residence duration, but no significant changes in iris thicknesses were observed. Although the subjects included in this study were adults, Gao Yunxian et al. [ 6 ] reported a tendency for smaller pupils in Uyghurs compared to Han individuals among adolescents and children. Compared to Han populations, Uyghurs demonstrated thicker irises and smaller constriction amplitudes. Previous studies [ 7 ] have indicated an independent negative correlation between iris thicknesses and pupil constriction amplitudes. Thicker irises may increase passive resistance during constriction, leading to diminished pupillary response. These ethnic differences may be partially determined by genetic factors, such as the OCA2 gene located at 15q11.2, which regulates melanin synthesis [ 8 ]. The rs12913832 allele of this gene shows higher frequency in Uyghurs[ 9 ], potentially enhancing the binding activity of microphthalmia-associated transcription factor (MITF), thereby promoting melanocyte differentiation and melanin synthesis, which may result in thickening of the iris stroma [ 10 ]. At the level of environmental adaptation, the southern Xinjiang region experiences long annual sunshine duration and intense ultraviolet radiation. Prolonged UV exposure may induce activation of inflammatory signaling pathways, promoting proliferation of iris stromal fibroblasts and collagen fiber deposition [ 11 ], which is consistent with the findings of increased iris thicknesses in Uyghur subjects in this study. Meanwhile, pupillary constriction as a light protection mechanism can reduce UV-induced oxidative damage to the lens and retina (there was a significant negative correlation between daily outdoor exposure time and pupil diameter, r=-0.352, r=-0.258, P < 0.01). This adaptive change is more pronounced in long-term settled populations. In this study, the Han population exhibited progressive pupil diameter reduction with prolonged residence duration: short-term residents (< 3 months) showed pupil diameters (4.63 ± 0.56 mm in darkness, 2.88 ± 0.53 mm in light) comparable to the mainland Han reference values (4.31 ± 0.76 mm in darkness, 2.54 ± 0.45 mm in light) [ 13 ]. In contrast, long-term Han residents (> 15 years) demonstrated reduced pupil diameters to 3.14 ± 0.52 mm in darkness and 2.18 ± 0.35 mm in light, while medium-term Han residents exhibited 3.88 ± 0.51 mm in darkness and 2.62 ± 0.47 mm in light, demonstrating a pronounced temporal gradient effect. This sequential impact may result from chronic ultraviolet exposure enhancing sensitivity of the pupillary light reflex pathway, leading to smaller pupil diameters. Significant changes in iris thickness only occurred in residents with over 15 years of residence, likely due to the prolonged collagen renewal cycle in iris stroma [ 14 ], where exposure within 5 years had not yet reached structural modification thresholds. Analysis of behavioral factor interactions revealed a positive correlation between outdoor exposure duration and pupil diameter as well as constriction amplitude. However, the impact of sunglasses usage rate was not statistically significant, suggesting that the direct effect of environmental exposure may outweigh behavioral interventions. This finding could also be attributed to inconsistent quality and expired usage of sunglasses among the general population, leading to uncertain and inconsistent ultraviolet (UV) blocking efficacy, which contributed to the observed result bias [ 15 ]. This study has several limitations: ① The small sample size results in low detection efficiency for micro-effect indicators such as iris thickness; ② The use of a single-timepoint cross-sectional design prevents analysis of dynamic trajectories in ocular characteristics over residence duration; ③ The absence of genotyping data hinders clarification of interaction patterns between genetic effects and environmental exposures; ④ Data collection spanned different seasons, making solar radiation variations a potential confounding factor that cannot be overlooked. Future studies focusing on seasonal data collection and incorporating solar duration as a covariate would enable more precise control of this influence. Future research can be further deepened in the following aspects: ① Adopting longitudinal cohort designs for long-term follow-up observations to establish temporal effect curves of pupillary diameter changes; ② Integrating genome-wide association analysis to stratify subgroups based on age and daylight exposure duration, thereby identifying specific factors associated with ultraviolet adaptation; ③ Investigating the unique challenges in diagnosis and treatment of ocular diseases in individuals with small pupils, such as intraocular lens measurements for cataract patients, particularly in populations with pupillary diameters < 3 mm, including selection of multifocal intraocular lens types and enhanced preoperative/intraoperative use of mydriatic agents. These explorations will contribute to elucidating the human eye's adaptation mechanisms to high ultraviolet environments and provide new theoretical foundations for the prevention of light-induced ocular diseases. Declarations Acknowledgments Not applicable. Statement of Ethics These protocols followed the tenets of the Declaration of Helsinki and written informed consent was obtained from all patients after they received a full explanation of the nature and possible consequences of the study. Conflict of Interest Statement The authors declare that there is not any conflict of interest regarding the publication of this paper. Funding Sources No funding was achieved for this study. Author contributions CH contributions to design of the study, acquisition of data, analysis and interpretation of data, and writing the article. FG contributions to the resolution of major issues and modification of the manuscript and carried out all the operations. ZC participated in the collection of patients and acquisition of data. GJ helped the collection of patients and conception and design. All authors read and agreed to the final manuscript. Clinical trial number Not applicable. References Wilson MH, Edsell M, Imray C,et al. Changes in pupil dynamics at high altitude--an observational study using a handheld pupillometer. High Alt Med Biol. 2008;9(4):319-325. DOI:10.1089/ham.2008.1026. Zhao Yong, Cui Caixia, Li Yang.Climatic characteristics of sunshine duration in the Tianshan mountains of Xinjiang[J]. Arid Zone Research,2011,28(04):688-693.DOI:10.13866/j.azr.2011.04.023. WangRF, ZhuSX, GuoZL,et al.The comprehensive geographical regionalization supporting natural conservation in Xinjiang.Acta EcologicaSinica, 2025,45(02):539-553.DOI:10.20103/j.stxb.202406121363. Z Mohammad,M Tahereh,R Hamid,et al.Automated measurement of iris surface smoothness using anterior segment optical coherence tomography[J]. 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Pan Y ，Zhang C ，Lu Y ，et al.Genomic diversity and post-admixture adaptation in the Uyghurs［J］.National Science Review.2022，9（03）：72-84. DOI:10.1093/nsr/nwab124. Wu M, Yavuzyigitoglu S, Brosens E, Ramdas WD, Kiliç E; Rotterdam Ocular Melanoma Study Group (ROMS). Worldwide Incidence of Ocular Melanoma and Correlation With Pigmentation-Related Risk Factors. Invest Ophthalmol Vis Sci. 2023;64(13):45. DOI:10.1167/iovs.64.13.45. Yao X，Liu BB，Liu J，et al．Research progress on the regulatory role of NF-kB signaling pathway in ophthalmic diseases．Guo ji Yan ke za zhi (Int Eye Sci),2024,24(11):1769—1773.DOI:10.3980/j.issn.1672-5123.2024.11.15. Roberts JE. Ultraviolet radiation as a risk factor for cataract and macular degeneration. Eye Contact Lens. 2011;37(4):246-249. DOI:10.1097/ICL.0b013e31821cbcc9. Zheng C, de Leon JM, Cheung CY, et al. Determinants of pupil diameters and pupil dynamics in an adult Chinese population. Graefes Arch Clin Exp Ophthalmol. 2016;254(5):929-936. DOI:10.1007/s00417-016-3272-7. Rada JA , Achen VR , Rada K G.Proteoglycan turnover in the sclera of normal and experimentally myopic chick eyes.[J].Invest Ophthalmol Vis,1998,39(11):1990-2002. Rabbetts R, Sliney D.Technical Report:Solar Ultraviolet Protection from Sunglasses[J].Optometry and Vision Science,2019,96(7):523-530.DOI:10.1097/OPX.0000000000001397 Additional Declarations No competing interests reported. Supplementary Files 1.xlsx 1.sav Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 19 Apr, 2026 Editor invited by journal 15 Apr, 2026 Editor assigned by journal 14 Apr, 2026 Submission checks completed at journal 14 Apr, 2026 First submitted to journal 13 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-9410208","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":628432347,"identity":"293ff61b-4011-4650-99bd-7beb349eac32","order_by":0,"name":"Haiting Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxklEQVRIie3PoQ6CUBTG8cPYLuUi9SbxEXBsFp3PAnODAmYim9tJjCxF38IZL2PTgt3NojNaoNGUYuZEN+8vnfD9wwFQlF+kcwA/hTEzNpKYGBlAm4I74iePmPAatCIFfyeiCa2wtnH1Mo+LECEC6JLDcCKu62Bu1kGMcJFaVt+GE0dEM9fEKkYt93QN6ck7ZDp3iAmv3UeB0mOMmohzHkCLqyly5pWkX6yNWTU+Lm17/yzvXUJIekx8L0na9/SGulQURflTH8seO98tVw7VAAAAAElFTkSuQmCC","orcid":"","institution":"Department of Ophthalmology and Otolaryngology, Luntai County People's Hospital","correspondingAuthor":true,"prefix":"","firstName":"Haiting","middleName":"","lastName":"Chen","suffix":""},{"id":628432348,"identity":"1c01d732-184c-4ee6-9a1d-fdf6d665f9fa","order_by":1,"name":"Guifang Fang","email":"","orcid":"","institution":"Department of Ophthalmology and Otolaryngology, Luntai County People's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Guifang","middleName":"","lastName":"Fang","suffix":""},{"id":628432349,"identity":"7c6a0a26-ddf5-4fd4-a255-ddc5f2b3277b","order_by":2,"name":"Chunmin Zhao","email":"","orcid":"","institution":"Department of Ophthalmology and Otolaryngology, Luntai County People's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chunmin","middleName":"","lastName":"Zhao","suffix":""},{"id":628432350,"identity":"f660b725-138c-4d90-a9b5-d41da52ac24e","order_by":3,"name":"Gulijiemilai Aierken","email":"","orcid":"","institution":"Department of Ophthalmology and Otolaryngology, Luntai County People's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gulijiemilai","middleName":"","lastName":"Aierken","suffix":""}],"badges":[],"createdAt":"2026-04-14 03:54:41","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9410208/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9410208/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108007752,"identity":"e50b1784-528b-4dd4-b97d-53b36f1c7ebc","added_by":"auto","created_at":"2026-04-28 13:01:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":238809,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9410208/v1/75b83598-4fda-45c0-ad69-8cb266094ee7.pdf"},{"id":107996770,"identity":"7621a844-0de7-45af-a865-2bf0eb196d1a","added_by":"auto","created_at":"2026-04-28 11:19:53","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":25563,"visible":true,"origin":"","legend":"","description":"","filename":"1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-9410208/v1/e7b75f15a51a5f9a966b4e7e.xlsx"},{"id":107996771,"identity":"c198794f-d961-4fd0-b808-a51082e020ae","added_by":"auto","created_at":"2026-04-28 11:19:53","extension":"sav","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":8165,"visible":true,"origin":"","legend":"","description":"","filename":"1.sav","url":"https://assets-eu.researchsquare.com/files/rs-9410208/v1/dee80bc1df3cd8cbab6906d1.sav"}],"financialInterests":"No competing interests reported.","formattedTitle":"Adaptive Changes in Pupil and Iris Morphology in Multi-ethnic Populations Exposed to High-Intensity Light in Luntai, Xinjiang","fulltext":[{"header":"Preface","content":"\u003cp\u003eResearch on the impact mechanisms of lighting environments on the human visual system is a crucial topic in the field of environmental health. Studies have shown that populations in plateau regions commonly exhibit physiological adaptive changes such as pupil constriction and iris thickening [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, for areas with lower altitudes but strong light characteristics, such as Xinjiang, China (annual average ultraviolet index UVI\u0026thinsp;\u0026gt;\u0026thinsp;8, sunshine duration exceeding 2800 hours) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], such adaptive-related research remains relatively scarce. Xinjiang possesses unique climatic and geographical features, including moderate latitude, arid climate, and high atmospheric transparency, which result in ultraviolet radiation intensity similar to that of high-altitude regions with thin air [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This provides ideal conditions for studying the effects of pure strong light on the human visual system.\u003c/p\u003e \u003cp\u003eWith regional socioeconomic development, environmental adaptability research has become a critical interdisciplinary topic spanning anthropology, medicine, and visual sciences. This study employs optical coherence tomography (OCT) technology [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] to non-invasively quantify iris structural characteristics across diverse populations, combined with standardized pupil measurements, to investigate the impact of long-term environmental adaptation on visual physiological functions. These findings not only enhance our understanding of human biodiversity but also hold significant practical implications for regional public health policy formulation and clinical ophthalmic diagnosis and treatment.\u003c/p\u003e"},{"header":"1 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e1.1 General Information\u003c/h2\u003e \u003cp\u003eThis study was conducted from January 2025 to December 2025 at the Ophthalmology Outpatient Department of LunTai County People's Hospital in Xinjiang. Healthy adults aged 18\u0026ndash;60 years were involved and divided into four groups based on continuous residence time and ethnicity: local Uyghur residents(continuous residence\u0026thinsp;\u0026gt;\u0026thinsp;18 years), long-term (continuous residence\u0026thinsp;\u0026gt;\u0026thinsp;15 years), medium-term (continuous residence 2\u0026ndash;5 years), and short-term Han Chinese residents (continuous residence\u0026thinsp;\u0026lt;\u0026thinsp;3 months). All participants underwent detailed ophthalmological examinations and systemic health assessments to exclude ocular diseases such as glaucoma and optic neuropathy, as well as systemic diseases affecting pupil size (e.g., diabetes and cerebrovascular diseases) and long-term medication history. The study adhered to the principles of the Helsinki Declaration and was approved by the hospital ethics committee (Luntai County People's Hospital Ethics Approval No.2025.4). All participants signed informed consent forms. The sample size was calculated with α\u0026thinsp;=\u0026thinsp;0.05 and β\u0026thinsp;=\u0026thinsp;0.1.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e1.2 Research Methods\u003c/h2\u003e \u003cp\u003eThis study adopted a cross-sectional research design, using standardized questionnaires to collect demographic characteristics, residential and occupational exposure histories, protective measures, and other information from participants: such as continuous residence time in Luntai; occupational types including indoor office work, mixed indoor-outdoor work, and outdoor work; average daily outdoor activity time; frequency of sunglasses use; ocular discomfort or diseases, etc. All participants underwent systematic eye examinations: visual acuity testing used a logarithmic visual acuity chart compliant with GB 11533\u0026thinsp;\u0026minus;\u0026thinsp;2011 standards, and anterior segment examination employed a Lanling KJ5E slit lamp microscope. Pupillary diameters were measured using smartphone video analysis: all measurements were conducted in a dark room with constant lighting (illuminance\u0026thinsp;\u0026lt;\u0026thinsp;5 lux). Participants were required to adapt to the dark environment for at least 10 minutes to ensure stable pupil size, fixing their gaze on distant targets while avoiding near-vision activities requiring accommodation and convergence, such as reading or using mobile phones. Participants sat with their corneas 30 cm from the lens, looking straight at the phone screen. The LED light source (100 lux) automatically activated at frame 10 of the video (lasting 5 seconds) and recorded continuously for 10 seconds (1 second before stimulation\u0026thinsp;+\u0026thinsp;4 seconds after stimulation). Measurements were repeated three times with 2-minute intervals, recording pupillary diameters under illumination conditions to calculate the constriction amplitude. Iris thickness measurements were performed using the YG-100K SE Ophthalmic Optical Coherence Tomography Scanner. Imaging was conducted with a preset volumetric scanning protocol comprising 128 radial scans, each with a length of 16 mm and depth of 6 mm, at scanning angles ranging from 0\u0026deg;to 180\u0026deg; (with 45\u0026deg;intervals). The total iris thickness was determined by selecting the thickest section from four sectors (nasal, temporal, superior, and inferior) and calculating the average value [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. To ensure data quality, all equipment underwent daily calibration. The examinations were performed by two trained technicians using a dual-independent data entry method.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e1.3 Statistical Methods\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using SPSS 19.0 software. Age, outdoor activity duration, pupil diameter, constriction amplitude, and iris thickness were measured as continuous variables, expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. Normality and homogeneity of variance were assessed using one-way ANOVA. For continuous variables that met the normal distribution and homogeneity of variance criteria, between-group comparisons were conducted using independent samples t-test; multi-group comparisons employed one-way ANOVA, with post-hoc pairwise comparisons performed using Tukey test. For continuous variables that did not meet normal distribution or homogeneity of variance criteria, nonparametric tests (Kruskal-Wallis test) were applied to assess intergroup differences, followed by Mann-Whitney U test for pairwise comparisons. Gender and sunglasses usage frequency were categorical variables analyzed using chi-square test for differences and Mann-Whitney U test for pairwise comparisons. For correlations between two continuous variables, Pearson correlation analysis was used if both variables followed normal distribution; if one or more variables deviated from normal distribution, Spearman rank correlation analysis was employed. A P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"2. Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Basic Characteristics of Study Subjects\u003c/h2\u003e \u003cp\u003eThe study ultimately included 80 subjects with a total of 160 eyes, among whom 50 were male (62.5%) and 30 were female (37.5%). They were divided into four groups based on ethnicity and duration of residence, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e: The local Uyghur residents group (continuous residence\u0026thinsp;\u0026gt;\u0026thinsp;18 years) consisted of 40 individuals (24 males and 16 females), with an average age of (48.9\u0026thinsp;\u0026plusmn;\u0026thinsp;20.6) years; the long-term Han Chinese group comprised 40 individuals (continuous residence\u0026thinsp;\u0026gt;\u0026thinsp;15 years) (28 males and 12 females), with an average age of (58.5\u0026thinsp;\u0026plusmn;\u0026thinsp;19.7) years; the medium-term Han Chinese group included 40 individuals (continuous residence 2\u0026ndash;5 years) (22 males and 18 females), with an average age of (55.2\u0026thinsp;\u0026plusmn;\u0026thinsp;18.4) years; and short-term Han Chinese residents group (continuous residence\u0026thinsp;\u0026lt;\u0026thinsp;3 months) consisted of 40 individuals (26 males and 16 females), with an average age of (53.1\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4) years. There were no statistically significant differences in age (F\u0026thinsp;=\u0026thinsp;4.913, p\u0026thinsp;=\u0026thinsp;0.178) or gender composition (χ\u0026sup2;=2.133, p\u0026thinsp;=\u0026thinsp;0.545) among the four groups.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGeneral characteristics of study subjects\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eGender(Male /Female)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLocal Uyghur residents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLong-term Han Chinese residents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMedium-term Han Chinese residents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eShort-term Han Chinese residents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e24/16\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e28/12\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e22/18\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e26/16\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.545\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge(year)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e48.9\u0026thinsp;\u0026plusmn;\u0026thinsp;20.6\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e58.5\u0026thinsp;\u0026plusmn;\u0026thinsp;19.7\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e55.2\u0026thinsp;\u0026plusmn;\u0026thinsp;18.4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e53.1\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.178\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Pupillary Adaptation Changes Under Intense Light Conditions\u003c/h2\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, under darkroom and standard bright light conditions, the pupillary diameters of Uyghur residents was generally smaller than that of long-term Han Chinese residents. Long-term Han Chinese residents (\u0026gt;\u0026thinsp;15 years) exhibited smaller pupillary diameters compared to medium-term group (2\u0026ndash;5 years) who had smaller pupillary diameters than short-term residents (\u0026lt;\u0026thinsp;3 months). The Uyghur resident group demonstrated the smallest baseline pupillary diameters, with significantly lower contraction amplitudes under light stimulation compared to long-term Han Chinese residents. The pupillary contraction amplitudes increased sequentially among long-term Han Chinese residents, medium-term Han Chinese residents, and short-term Han Chinese residents, with statistically significant differences. This indicates that smaller baseline pupillary diameters had relatively limited contraction spaces, whereas larger pupillary diameters exhibit greater contraction amplitudes under light stimulation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Imaging characteristics of iris structures\u003c/h2\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, anterior segment OCT measurements revealed that the average iris thicknesses were greater in Uyghur residents compared to Han Chinese residents. Among Han Chinese residents, long-term residents exhibited significantly thicker iris stroma layers than medium-term or short-term residents, with statistically significant differences. Although medium-term Han Chinese resident showed slightly increased average iris thicknesses compared to short-term residents, the difference was not statistically significant.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBiological parameters of anterior segment in populations of different ethnicities and residence durations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLocal Uyghur residents\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLong-term Han Chinese residents\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMedium-term Han Chinese residents\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eShort-term Han Chinese residents\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTest\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePupillary diameter (dark) (mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;120.487\u003c/p\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eGroup comparison (Z-score)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5.615**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-7.699**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-7.699**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-5.168**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-7.347**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-5.206**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePupillary diameter (light) (mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;85.573\u003c/p\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eGroup comparison (Z-score)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-4.013**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-6.919**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-7.289**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4.230**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-5.707**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-2.377*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCompression amplitude (mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;104.859\u003c/p\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eGroup comparison (Z-score)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5.390**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-7.266**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-7.699**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4.279**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-6.419**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-4.283**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIris thickness (um)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e450.5\u0026thinsp;\u0026plusmn;\u0026thinsp;51.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e407.7\u0026thinsp;\u0026plusmn;\u0026thinsp;39.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e369.6\u0026thinsp;\u0026plusmn;\u0026thinsp;59.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e346.9\u0026thinsp;\u0026plusmn;\u0026thinsp;64.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;31.132\u003c/p\u003e \u003cp\u003eP\u0026thinsp;=\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eGroup comparison (P-score)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.205\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e*: \u003cem\u003eP\u003c/em\u003e\u0026lt;0.05 **༚\u003cem\u003eP\u003c/em\u003e\u0026lt;0.001\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Modifying Effects of Sunlight Exposure\u003c/h2\u003e \u003cp\u003eProlonged outdoor activity duration was associated with smaller pupil diameters (r=-0.352, r=-0.258) and reduced constriction amplitudes (r=-0.370) in darkroom and bright light conditions, respectively. However, the positive correlation with increased iris thicknesses (r\u0026thinsp;=\u0026thinsp;0.134) was not statistically significant. Other factors such as gender, age, and sunglasses usage showed no significant correlation with pupil or iris thickness (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelation between factors and biological parameters of the anterior segments\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePupillary diameter (dark) (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOutdoor time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSunglasses\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.824\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.280\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.609\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePupillary diameter (light) (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.652\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.641\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.472\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompression amplitude (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.685\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.516\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIris thickness (um)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.437\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.578\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.090\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.843\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*: \u003cem\u003eP\u003c/em\u003e\u0026lt;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Discussion","content":"\u003cp\u003eThis study explored the ocular parameter characteristics of different populations (local Uyghurs, long-term Han residents, medium-term Han residents, and short-term residents) in Luntai, Bayingolin Mongolian Autonomous Prefecture, Xinjiang, through a cross-sectional design. The indicators included pupil diameter, pupillary constriction amplitude, and iris thickness, demonstrating the effects of ethnic groups and residence duration on ocular physiological features. It also suggested potential adaptive changes in the eyes under high ultraviolet radiation environments.\u003c/p\u003e \u003cp\u003eThis study found that the Uyghur population exhibited characteristics of smaller pupil diameters, reduced constriction amplitudes, and increased iris thicknesses compared to Han residents. In contrast, Han populations showed adaptive reduction in pupil diameters with prolonged residence duration, but no significant changes in iris thicknesses were observed. Although the subjects included in this study were adults, Gao Yunxian et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] reported a tendency for smaller pupils in Uyghurs compared to Han individuals among adolescents and children. Compared to Han populations, Uyghurs demonstrated thicker irises and smaller constriction amplitudes. Previous studies [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] have indicated an independent negative correlation between iris thicknesses and pupil constriction amplitudes. Thicker irises may increase passive resistance during constriction, leading to diminished pupillary response. These ethnic differences may be partially determined by genetic factors, such as the OCA2 gene located at 15q11.2, which regulates melanin synthesis [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The rs12913832 allele of this gene shows higher frequency in Uyghurs[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], potentially enhancing the binding activity of microphthalmia-associated transcription factor (MITF), thereby promoting melanocyte differentiation and melanin synthesis, which may result in thickening of the iris stroma [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAt the level of environmental adaptation, the southern Xinjiang region experiences long annual sunshine duration and intense ultraviolet radiation. Prolonged UV exposure may induce activation of inflammatory signaling pathways, promoting proliferation of iris stromal fibroblasts and collagen fiber deposition [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], which is consistent with the findings of increased iris thicknesses in Uyghur subjects in this study. Meanwhile, pupillary constriction as a light protection mechanism can reduce UV-induced oxidative damage to the lens and retina (there was a significant negative correlation between daily outdoor exposure time and pupil diameter, r=-0.352, r=-0.258, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). This adaptive change is more pronounced in long-term settled populations.\u003c/p\u003e \u003cp\u003eIn this study, the Han population exhibited progressive pupil diameter reduction with prolonged residence duration: short-term residents (\u0026lt;\u0026thinsp;3 months) showed pupil diameters (4.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56 mm in darkness, 2.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53 mm in light) comparable to the mainland Han reference values (4.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76 mm in darkness, 2.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45 mm in light) [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In contrast, long-term Han residents (\u0026gt;\u0026thinsp;15 years) demonstrated reduced pupil diameters to 3.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52 mm in darkness and 2.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35 mm in light, while medium-term Han residents exhibited 3.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 mm in darkness and 2.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47 mm in light, demonstrating a pronounced temporal gradient effect. This sequential impact may result from chronic ultraviolet exposure enhancing sensitivity of the pupillary light reflex pathway, leading to smaller pupil diameters. Significant changes in iris thickness only occurred in residents with over 15 years of residence, likely due to the prolonged collagen renewal cycle in iris stroma [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], where exposure within 5 years had not yet reached structural modification thresholds.\u003c/p\u003e \u003cp\u003eAnalysis of behavioral factor interactions revealed a positive correlation between outdoor exposure duration and pupil diameter as well as constriction amplitude. However, the impact of sunglasses usage rate was not statistically significant, suggesting that the direct effect of environmental exposure may outweigh behavioral interventions. This finding could also be attributed to inconsistent quality and expired usage of sunglasses among the general population, leading to uncertain and inconsistent ultraviolet (UV) blocking efficacy, which contributed to the observed result bias [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study has several limitations: ① The small sample size results in low detection efficiency for micro-effect indicators such as iris thickness; ② The use of a single-timepoint cross-sectional design prevents analysis of dynamic trajectories in ocular characteristics over residence duration; ③ The absence of genotyping data hinders clarification of interaction patterns between genetic effects and environmental exposures; ④ Data collection spanned different seasons, making solar radiation variations a potential confounding factor that cannot be overlooked. Future studies focusing on seasonal data collection and incorporating solar duration as a covariate would enable more precise control of this influence.\u003c/p\u003e \u003cp\u003eFuture research can be further deepened in the following aspects: ① Adopting longitudinal cohort designs for long-term follow-up observations to establish temporal effect curves of pupillary diameter changes; ② Integrating genome-wide association analysis to stratify subgroups based on age and daylight exposure duration, thereby identifying specific factors associated with ultraviolet adaptation; ③ Investigating the unique challenges in diagnosis and treatment of ocular diseases in individuals with small pupils, such as intraocular lens measurements for cataract patients, particularly in populations with pupillary diameters\u0026thinsp;\u0026lt;\u0026thinsp;3 mm, including selection of multifocal intraocular lens types and enhanced preoperative/intraoperative use of mydriatic agents. These explorations will contribute to elucidating the human eye's adaptation mechanisms to high ultraviolet environments and provide new theoretical foundations for the prevention of light-induced ocular diseases.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement of Ethics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThese protocols followed the tenets of the Declaration of Helsinki and written informed consent was obtained from all patients after they received a full explanation of the nature and possible consequences of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there is not any conflict of interest regarding the publication of this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Sources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was achieved for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCH contributions to design of the study, acquisition of data, analysis and interpretation of data, and writing the article. FG contributions to the resolution of major issues and modification of the manuscript and carried out all the operations. ZC participated in the collection of patients and acquisition of data. GJ helped the collection of patients and conception and design. All authors read and agreed to the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWilson MH, Edsell M, Imray C,et al. Changes in pupil dynamics at high altitude--an observational study using a handheld pupillometer. High Alt Med Biol. 2008;9(4):319-325. DOI:10.1089/ham.2008.1026.\u003c/li\u003e\n\u003cli\u003eZhao Yong, Cui Caixia, Li Yang.Climatic characteristics of sunshine duration in the Tianshan mountains of Xinjiang[J]. Arid Zone Research,2011,28(04):688-693.DOI:10.13866/j.azr.2011.04.023.\u003c/li\u003e\n\u003cli\u003eWangRF, ZhuSX, GuoZL,et al.The comprehensive geographical regionalization supporting natural conservation in Xinjiang.Acta EcologicaSinica, 2025,45(02):539-553.DOI:10.20103/j.stxb.202406121363.\u003c/li\u003e\n\u003cli\u003eZ Mohammad,M Tahereh,R Hamid,et al.Automated measurement of iris surface smoothness using anterior segment optical coherence tomography[J]. Scientific Reports.2021,11(1):8505-8505.DOI： 10.1038/S41598-021-87954-W.\u003c/li\u003e\n\u003cli\u003eInvernizzi A, Giardini P, Cigada M, et al. Three-Dimensional Morphometric Analysis of the Iris by Swept-Source Anterior Segment Optical Coherence Tomography in a Caucasian Population. Invest Ophthalmol Vis Sci. 2015;56(8):4796-4801. DOI:10.1167/iovs.15-16483.\u003c/li\u003e\n\u003cli\u003eGao YX, Li XL, Ma XL, et al. Investigation and analysis of myopia and ocular biological parameters of primary and secondary school students in Urumqi. Guoji Yanke Zazhi( Int Eye Sci) 2023,23(03):471-476.DOI:10.3980/j.issn.1672-5123.2023.3.24.\u003c/li\u003e\n\u003cli\u003eSharma S, Baskaran M, Rukmini AV, et al. Factors influencing the pupillary light reflex in healthy individuals. Graefes Arch Clin Exp Ophthalmol. 2016;254(7):1353-1359. DOI:10.1007/s00417-016-3311-4。\u003c/li\u003e\n\u003cli\u003ePerez Palomeque G, Khacha-Ananda S, Monum T, Wunnapuk K. Prediction of Skin Color Using Forensic DNA Phenotyping in Asian Populations: A Focus on Thailand. Biomolecules. 2025;15(4):548.DOI:10.3390/biom15040548.\u003c/li\u003e\n\u003cli\u003ePan Y ，Zhang C ，Lu Y ，et al.Genomic diversity and post-admixture adaptation in the Uyghurs［J］.National Science Review.2022，9（03）：72-84. DOI:10.1093/nsr/nwab124.\u003c/li\u003e\n\u003cli\u003eWu M, Yavuzyigitoglu S, Brosens E, Ramdas WD, Kili\u0026ccedil; E; Rotterdam Ocular Melanoma Study Group (ROMS). Worldwide Incidence of Ocular Melanoma and Correlation With Pigmentation-Related Risk Factors. Invest Ophthalmol Vis Sci. 2023;64(13):45. DOI:10.1167/iovs.64.13.45.\u003c/li\u003e\n\u003cli\u003eYao X，Liu BB，Liu J，et al．Research progress on the regulatory role of NF-kB signaling pathway in ophthalmic diseases．Guo ji Yan ke za zhi (Int Eye Sci),2024,24(11):1769\u0026mdash;1773.DOI:10.3980/j.issn.1672-5123.2024.11.15.\u003c/li\u003e\n\u003cli\u003eRoberts JE. Ultraviolet radiation as a risk factor for cataract and macular degeneration. Eye Contact Lens. 2011;37(4):246-249. DOI:10.1097/ICL.0b013e31821cbcc9.\u003c/li\u003e\n\u003cli\u003eZheng C, de Leon JM, Cheung CY, et al. Determinants of pupil diameters and pupil dynamics in an adult Chinese population. Graefes Arch Clin Exp Ophthalmol. 2016;254(5):929-936. DOI:10.1007/s00417-016-3272-7.\u003c/li\u003e\n\u003cli\u003eRada JA , Achen VR , Rada K G.Proteoglycan turnover in the sclera of normal and experimentally myopic chick eyes.[J].Invest Ophthalmol Vis,1998,39(11):1990-2002.\u003c/li\u003e\n\u003cli\u003eRabbetts R, Sliney D.Technical Report:Solar Ultraviolet Protection from Sunglasses[J].Optometry and Vision Science,2019,96(7):523-530.DOI:10.1097/OPX.0000000000001397\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Pupil, Tomography, Optical Coherence, Ethnicity, Environmental Exposure","lastPublishedDoi":"10.21203/rs.3.rs-9410208/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9410208/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo assess pupillary and iris structural differences between Uyghur and Han populations with different residence durations in southern Xinjiang.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eIn this cross-sectional study, 80 healthy adults (160 eyes) were grouped by ethnicity and residence duration. Pupil metrics were obtained using smartphone video analysis; iris thickness was measured by anterior segment OCT. Questionnaire data on light exposure and protection were collected. Statistical analyses included ANOVA, nonparametric tests, and linear regression.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThere were no significant differences in demographic characteristics among the four groups. The Uyghur group had smallest pupil diameters and most reduced constriction amplitudes. With the extension of residence time, the pupil diameters of the Han population showed a gradient decrease (short-term\u0026thinsp;\u0026gt;\u0026thinsp;new migration\u0026thinsp;\u0026gt;\u0026thinsp;long-term), and the contraction amplitudes decreased simultaneously. The iris thickness of the Uyghur group was greater than that of the Han group,while the iris thickness of the long-term resident Han group was significantly thicker than that of the newly migrated and short-term groups. Outdoor exposure negatively correlated with pupil diameter but not with iris thickness.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eProlonged light exposure in Xinjiang may lead to pupillary constriction and iris thickening, showing ethnic and duration-dependent adaptations.\u003c/p\u003e","manuscriptTitle":"Adaptive Changes in Pupil and Iris Morphology in Multi-ethnic Populations Exposed to High-Intensity Light in Luntai, Xinjiang","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-28 11:19:47","doi":"10.21203/rs.3.rs-9410208/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2026-04-20T01:20:50+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-15T12:03:07+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-14T09:59:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-14T09:58:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Ophthalmology","date":"2026-04-14T03:44:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e2b86696-0a09-492e-808f-b8fc34853b2d","owner":[],"postedDate":"April 28th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-28T11:19:47+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-28 11:19:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9410208","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9410208","identity":"rs-9410208","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}