Prevalence and associated risk factors for childhood strabismus in Lhasa, Tibet, China: a cross-sectional, school-based study

Abstract Background: To estimate the prevalence of strabismus and associated risk factors among grade one school children in Lhasa, Tibet, China. Methods: The Lhasa Childhood Eye Study (LCES) was a cross-sectional, school-based childhood study conducted in Grade one students from primary schools in Lhasa, Tibet, China. Comprehensive ophthalmic examinations and basic systematic examinations were evaluated. A questionnaire survey contained information about children, as well as parents’ information was sent to the corresponding parents of eligible children. The prevalence of strabismus and its 95% confidence interval was estimated. Univariate and multivariate logistic regression analyses were conducted to determine the associated risk factors. Results: A total of 1942 eligible grade one students were enrolled, of which 1856 participants completed all procedures. The average age was 6.83±0.46 years, 53% of participants were boys and 1762 were the Tibetan Minority. Over all, the prevalence of strabismus was 68/1856(3.7%) (95%CI: 2.81,4.52), with no difference between the ages, genders, ethnics and BMI, while tilt one's head when writing may be a risk factor for strabismus ( P =0.004). Strabismus students had the mean best corrected visual acuity 0.16±0.28(LogMAR), over 50% patients with esotropia are hyperopia, participants who have stereopsis impairments showed a significant difference between esotropia and exotropia ( P= 0.026). Conclusions: The prevalence of strabismus in LCES was 3.7%, higher than previous reports from Chinese childhood epidemiology studies. Strabismus is a common contributing factor to amblyopia. Tilt one's head when writing may be a risk factor. Patients with esotropia are more likely to affect stereopsis and be the refractive state of hyperopia.