Prevalence of refractive error in mentally retarded students of Kathmandu Valley

Mental retardation also known as 'mentally handicap' means a delay or insufficient development of mental capacities. The prevalence of mental retardation in Nepal is 4.1%. Vision being the best sense for their education and daily activities, a cross-sectional and descriptive study was conducted to find out the refractive error among the students in the schools for mentally retarded people. A total of 134 clinically diagnosed cases of mentally retarded students from three different schools of Kathmandu Valley were examined. Distance visual acuity was taken with the help of Cat Ford Vision Drum, SG chart and Kay Picture Test method but first preference was given to SG chart. Cyclo-retinoscopy and fundus examination under mydriasis were done in all the cases. Examination revealed that more than half of the examined had one or more ocular disorders with refractive error being the most common type of ocular morbidity followed by ocular motility disorders. Refractive errors were found in 34.4% in which the most common type of refractive error was simple hypermetropia. In conclusion refractive error was seen commonly among mentally retarded people of Kathmandu Valley.