Causes of Blindness and Low Vision in Schools for Students With Visual Impairments in Tehran

Introduction: Childhood visual impairment is a global concern. We aimed to identify the major causes of childhood visual impairment in schools for students with visual impairments in Tehran, Iran. Methods: This cross-sectional study was conducted on students attending two schools for students with visual impairments in Tehran. All students or their guardians were interviewed to record their past medical history. Students underwent comprehensive ocular examinations, including assessment of presenting visual acuity, eye fixation status, color vision, external ocular exam, and examinations of anterior and posterior ocular segments. The classification of visual impairment was conducted based on the definitions provided by the World Health Organization International Classification of Diseases, and the exact cause of visual impairment was recorded. Results: A total of 134 students, whose average age was 13.52 ± 2.9 years (range, 7 to 18 years) and who were primarily female (56.7%), participated. More than 82.8% of participants had blindness (1.3 to 3.1 LogMAR, < 3/60), 4.4% had severe visual impairment (1.0 to 1.3 LogMAR; 3/60-6/60), and 12.8% had moderate visual impairment (0.48 to 1.0 LogMAR; 6/60-6/18). The retina (47.1%), optic nerve (17.9%), and whole globe (10.5%) were the most affected anatomical sites, with Leber's congenital amaurosis (a hereditary retinal disorder) being the most prevalent diagnosis (27.8%), followed by optic nerve atrophy (17.9%), congenital glaucoma (9.7%), phthisis eye (5.2%), and microphthalmos (5.2%). We found parental consanguinity in 68.42% of cases with hereditary retinal disorders. Discussion: In the current study, hereditary retinal disorders were among the most prevalent causes of visual impairment, which can be attributed to the high rates of consanguineous marriages in Iran. Implications for Practitioners: The current findings highlight the need to provide an educational program to raise awareness in our society about the hereditary causes of visual impairment, particularly as a potential result of autosomal recessive genetic disorders.