Prevalence of visual impairment and related factors in Nangarhar Province of Afghanistan: a cross sectional study

To determine the prevalence, main causes, and related factors of visual impairment (VI) among people aged 50y and over in Jalalabad City and four surrounding districts of Nangarhar Province of Afghanistan. The data for the population based cross-sectional study was collected in 2015. The calculated sample size was 1353, allocated to urban-rural strata using probability proportion to size method. At the end of the study, 1281 people participated in to the study. VI was defined as presenting visual acuity (VA) of less than 6/18 and blindness as VA less than 3/60 in the better eye by using Snellen chart only. Data was analyzed using IBM SPSS 21.0 software. The prevalence of VI was 22.6% (95%CI, 20%-25%) of which 13.9% (95%CI, 12%-16%) was low vision and 8.7% (95%CI, 7%-10%) was blindness. The most common causes of the VI were cataract (52.8%), followed by uncorrected refractive error (URE) (26.9%) and glaucoma (8.6%). Number one cause of the low vision was URE (42%), followed by cataract, glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR), while for blindness they are cataract (72%), other posterior segment disorders, glaucoma, URE and AMD. Illiteracy, bad economic status, hypertension and overweight were factors independently associated with both VI and low vision, whereas, age, illiteracy, bad economic status, hypertension and using of sunglasses were independently associated with blindness. Cataract, URE, glaucoma, AMD and DR are the leading causes of VI and blindness in the study area. They are mostly avoidable. In order to decrease the burden of VI and blindness in the study area as well as the whole country, it is strongly recommended to apply the prevention policies of VI and blindness.