The Prevalence of Amblyopia among 7-12 year old Primary School Children of Tehran, Iran in 2013

To determine the screening prevalence of amblyopia, refractive errors and strabismus among 7 to 12 year-old primary school children, Tehran, Iran, in 2013. This population based cross sectional study was performed on randomly selected 2410 students from 40 primary schools. Visual acuity was measured using Yang vision tester Snellen E-optotype. If visual acuity was 20/40, the measurements were repeated using a Pinhole. Refractive error was measured by photorefractometer without cycloplegia. Strabismus was checked using cover test and extraocular muscle function tests. Direct ophthalmoscope was used to evaluate the anterior segment, lens opacities, red reflex and fundus. Amblyopia was defined as optimal VA (Pinhole VA) 20/40 in one or both eyes while there were no anatomical problems. Amblyopia was found in 2.3% of participants with no gender difference. It was significantly higher among younger children (p=0.004). The prevalence of hyperopia +2.00D, myopia-0.50D, astigmatism 0.75D and anisometropia (SE difference 1.00D) were 3.5%, 4.9%, 22.7% and 3.9%, respectively. Amblyopia was present in 15.9% of hyperopic and 5.9% of myopic cases. Older age was associated with higher myopia (p<0.001) and lower hyperopia (p<0.029), while astigmatism had no significant difference among the age groups. Strabismus was found in 2.3% of cases. Strabismus, refractive errors especially anisometropia and hyperopia were important risk factors for the development of amblyopia. Compared to developed countries (0.7%), the prevalence of amblyopia (2.3%) was higher in this urvey which highlights the importance of applying on-time and sensitive screening methods. Due to high revalence of amblyopia among children with refractive errors, it is suggested to provide free of charge lasses for free among children younger than 10.