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The association between iris color and refractive errors in children
Mehrdad Ebrahimi1, Anneh Mohammad Gharravi2, Roqayeh Aliyari3
1Student Research Committee, School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran.
Insights
Children with amber irises have a significantly higher chance of developing myopia. This finding suggests closer monitoring for these children and warrants further research into iris color and vision development.
Area of Science:
- Ophthalmology
- Pediatric Ophthalmology
- Genetics
Background:
- Refractive errors like myopia and hyperopia are significant global health concerns in children.
- Iris color, a genetically influenced trait, has been anecdotally linked to vision conditions, but robust evidence is limited.
- Understanding potential associations can aid in early detection and intervention strategies for childhood vision impairment.
Purpose of the Study:
- To investigate the association between various iris colors and the prevalence of myopia and hyperopia in children aged 6-12 years.
- To identify specific iris color phenotypes that may correlate with an increased risk of refractive errors.
- To provide data that could inform targeted screening programs for at-risk children.
Main Methods:
- A cross-sectional study utilizing data from the Shahroud Schoolchildren Eye Cohort Study.
- Iris color was categorized using standardized close-up images.
- Myopia and hyperopia were defined based on cycloplegic refraction spherical equivalent (SE) values.
- Multiple logistic regression models were employed, adjusting for relevant covariates like age, sex, residence, and visual activity.
Main Results:
- The study included 5394 children with a mean age of 9.7 years; myopia prevalence was 4.8% and hyperopia was 4.7%.
- Amber iris color showed a statistically significant association with higher odds of myopia (Odds Ratio = 4.8, 95% CI: 1.2-18.7) compared to dark brown irises.
- No significant associations were found between iris color and hyperopia.
Conclusions:
- Amber iris color is a potential risk factor associated with an increased likelihood of myopia in children.
- Children with amber irises may benefit from closer ophthalmological monitoring and regular eye examinations.
- Further research with larger sample sizes across diverse populations and iris colors is recommended to confirm these findings.
Abstract:
This study aimed to evaluate the association between iris color and refractive errors in children aged 6-12 years. This cross-sectional study was based on data obtained from the first phase of the Shahroud Schoolchildren Eye Cohort Study. The target population was 6 to12 year-old students living in urban and rural areas. Iris colors were classified by comparing eye colors with close-up images of iris colors. Myopia was defined as a spherical equivalent (SE) ≤ - 0.5 diopter and hyperopia was defined as SE ≥ 2 diopter in cycloplegic refraction. The association of iris color with hyperopia and myopia was investigated by fitting two separate multiple logistic regression models adjusted for place of residence, age, sex, and times for outdoor activity and near work. Among the 5394 participates with the mean age of 9.7 year, the prevalence of myopia and hyperopia was 4.8% and 4.7% respectively. The number and proportion (in parentheses) of amber, light blue, light brown, dark brown, gray, green and hazel iris colors were 19(0.4%), 26(0.5%), 645(12.0%), 4517(83.7%), 4(0.1%), 59(1.1%), and 124(2.3%) respectively. Compared to dark brown, the odds ratios and 95% confidence intervals (in parentheses) of myopia were 4.8(1.2-18.7), 0.8(0.1-5.8), 1.0(0.7-1.5), 0.4(0.1-2.7) and 0.6(0.2-1.8) for amber, light blue, light brown, green and hazel iris colors in multiple logistic regression model. No significant association was observed between iris colors and hyperopia. This study shows that amber iris is significantly associated with higher odds of myopia. These children should be further monitored and examined. More studies with higher sample size in all iris colors are recommended.
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