This population-based cross-sectional study investigates the prevalence and demographics of lower eyelid epiblepharon and explores its correlation with refractive errors in 3–6 year-old Chinese children. To the best of our knowledge, this study for the first time discloses the prevalence of this eyelid disorder in Chinese preschoolers and analyzes the relationship between epiblepharon and refractive errors including not only astigmatism but also myopia and hyperopia. We observe an prevalence of 26.2% in 3–6 year-old Chinese children, much higher than Noda S. et al’s study in Japanese where 13.8% of the 766 children at the age of 3–6 years old are diagnosed with epiblepharon3. We assume the relatively lower prevalence in Noda’s study is possibly owing to that they adopted a relatively strict criteria for disease diagnosis when the widely-accepted Khwarg’s classification has yet been established then based on the following clues. First of all, when we excluded children with mild epiblephaorn, the prevalence decreased to 11.9% which is similar to 13.8% as reported in the Japanese children. Second, in their study, the cilia-cornea touching was confirmed only when the cornea is positively stained after topical fluorescein staining; whereas, later studies by Khwang S. et al and Young S. et al indicate that a considerable number of epiblepharon (usually mild epiblepharon) may not have the ocular manifestation of corneal erosion that could be stained with fluorescein8,13.
Given such a high prevalence in Asian infants and children, deducing the demographic characteristics of epiblepharon is helpful for a better understanding of this eyelid disorder. Till now, limited data are available based on either observations of general population3,7 or retrospective data from patients that underwent surgical treatment4. Agreed with those previous studies3,4,7, our results in Chinese preschool children show that the younger have a higher risk of epiblepharon comparing to the older, supporting the widely-accepted hypothesis that the anatomical defects in Asians decrease with facial bone growth and thus epiblepharon tends to disappear spontaneously with aging6. Whereas, there are discrepancies in the sexual predilection between our study and others. Different from results in Japanese and Singaporeans where no sexual predilection was recognized3,4,7, the present study demonstrates that boys are subject to a higher risk of having lower eyelid epiblepharon than girls with an adjusted OR = 1.41 in the multivariate logistic regression model. Differences in the diagnostic criteria3, subjects’ age range7, epiblepharon severity, as well as possible sample selection bias in a clinic-based study4 may all contribute to the discrepancy in sex predilection between our study and others.
We also evaluated the relationship between BMI and epiblepharon. Our results showed that epiblepharon children have slightly higher BMI than nonepiblepharon children; whereas, after adjustment of age and gender in the regression analysis, the difference was no-longer statistically significant. Furthermore, we compared the BMI between epiblepharon and nonepiblepharon children in boys and girls, respectively, and none of the groups gives a statistically significant difference in BMI (data not shown). Comparing to previous studies where the relation between epiblepharon and BMI has been reported in 6–14 year-old Japanese7, 6–15 years Korean10 and 1–12 year-old Chinese5 without achieving a consensus themselves, our results are partly in agreement with the Chinese study where no statistically significant differences in BMI are detected between epiblephaorn and noepiblepharon girls5. In boys, the BMI of epiblepharon children do be slightly higher than that of nonepiblepharon children, yet without statistical significance (15.44 vs 15.32; data not shown). The reason why we did not recognize a correlation between epiblepharon and high BMI in preschool boys as in that study is possibly owing to the differences in age, gender, sample size and epiblepharon severity between our population-based study and that clinic-based study5.
Although lower eyelid epiblepharon has a trend to resolve spontaneously with age, its occurrence during the critical period of visual development makes it crucial to disclose if it is correlated with refractive errors, which may ultimately lead to permanent visual impairment such as amblyopia or retinopathy14–17. In this study, the overall prevalence of astigmatism (CYL ≥ 1.5 D) in Chinese preschoolers is 9.68%, similar to the previous reported 8.2–8.3% in Asian infants and preschoolers18–20; by contrast, in those with lower eyelid epiblepharon which is unknown till now, the prevalence could be as high as 18.9%, 34.8%, or 72.8% when astigmatism was defined as CYL ≥ 1.5 D, CYL ≥ 1.0 D, or CYL ≥ 0.5 D, respectively. In this study, using data from general population we disclose for the first time that epiblepharon children are subject to a significantly higher risk of astigmatism, largely being with-the-rule, and these findings agree well with previous retrospective studies in clinical patients9,11,12. What’s more, the epiblepharon severity is positively associated with the astigmatism severity. According to previous research on astigmatism genesis, the high risk of astigmatism in particular WTR astigmatism in epiblepharon children may result from the change in corneal curvature by eyelid pressure from abnormal horizontal skinfold and eyelid squeezing from corneal irritation8,21.
In addition, we also evaluated the relationship between lower eyelid epiblepharon and spherical refractive errors, i.e. myopia and hyperopia, which has not been disclosed in previous studies. These epiblepharon preschoolers are as 3.55 times likely to have myopia as those without epiblepharon, and as 1.53 times likely to have hyperopia. The significantly increased risk of myopia in epiblepharon children agrees with the observations in clinical patients that severe myopia commonly accompanied with a large number of cilia touching the cornea9. Whereas, considering the relatively small sample size (22 out of 39 epiblepharon preschoolers being myopic) and absence of severe myopia (-2.75 D to -0.5 D), further study with a larger sample size and stratified by myopia severity level should be conducted to further validate the association between epiblepharon and myopia.
The strength of this study lies in that the demographics of epiblepharon and its correlation with refractive errors are evaluated in Chinese preschool population with by far the largest sample size. Nevertheless, there are several limitations in this study. First, the children included in this study are all enrolled from urban area, which may result in bias from sample selection. Further studies ideally from multicenters including children from both rural and urban area would improve our understandings on the risk factors related to lower eyelid epiblepharon and its association with refractive errors. Second, the prevalence of epiblepharon may be underestimated because children can be missed out for epiblepharon when their cilia touching the cornea only in downward gaze but not in primary gaze. Another limitation is that we use only the skinfold height and the cilia-cornea touching area as criteria for the diagnosis of lower eyelid epiblepharon without considering areas of corneal erosion. Whereas, owing to the concerns on the risk of fluorescein dying procedure and limited time allowance in a screening circumstance, an approach both safe and simple must be adopted; besides, this limitation can be mitigated since there are high agreement among the three criteria for the diagnosis of epiblepharon8. In addition, we did not evaluate the visual impairment such as amblyopia in this population and thus this part of work will be open for further study.
In conclusion, our study demonstrates a relatively high prevalence of lower eyelid epiblehaorn in Chinese preschoolers, particularly in boys and young children, and shows that there are significant correlations between lower eyelid epiblepharon and refractive errors including astigmatism, myopia, and hyperopia. Given such a high prevalence combined with the increased risk for refractive errors, it would be of great significance to be aware of the necessity and importance to establish an effective screening strategy for this disease, to conduct a closer follow-up of the clinical manifestations of involved children, and to consider giving early interventions and visual rehabilitation when warranted.