Abstract
Purpose:To determine the prevalence of amblyopia and refractive errors among 7 to 12-year-old primary school children in Tehran, Iran.Methods:This population-based cross-sectional study included 2,410 randomly selected students. Visual acuity was tested using an E-chart on Yang vision tester. Refractive errors were measured by photorefractometry and cycloautorefraction. Strabismus was checked using cover test. Direct ophthalmoscopy was used to assess the anterior segment, lens opacities, red reflex and fundus. Functional amblyopia was defined as best corrected visual acuity ≤20/40 in one or both eyes with no anatomical problems.Results:Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9%) of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004). Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D) was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001), that of hyperopia decreased (P=0.007), but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9) and refractive errors, especially anisometropia (OR=12.87) and hyperopia (OR=11.87), were important amblyogenic risk factors.Conclusion:The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.
Highlights
Amblyopia results from abnormal development of the visual system in early childhood
Amblyopia was diagnosed in 56 subjects (2.3%, 95% CI: 1.8% to 2.9%) who had best corrected visual acuity (BCVA) ≤20/40
Strabismus was present in 2.3% of the examined population, including esotropia in 1% and exotropia in 1.3%
Summary
Amblyopia results from abnormal development of the visual system in early childhood. The visual cortex needs continuous, clear and focused visual impulses to develop normally.[1,2,3,4,5,6,7] Children with amblyogenic risk factors, if not treated, are vulnerable to functional. Accepted: 02-06-2015 reduction of visual acuity (VA), causing amblyopia.[1,2,3] The prevalence of amblyopia in the literature ranges from 0.7% to 5%, depending on the characteristics of study population, visual acuity criteria and measurement methods.[8,9,10,11] Amblyopia is the most common cause. Journal of Ophthalmic and Vision Research 2015; Vol 10, No 4
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