Prevalence of Refractive Error in Mentally Retarded Students of Kathmandu Valley

Abstract

Background: Mental retardation is seen all over the world. As mental disorder is a developmental disorder and refractive error can develop by ocular mal-development, high percentage of refractive error could be found in mentally retarded students, which has been never explored in Nepal. Simple correction with glasses can improve their vision that can be utilized by both the trainer to teach them for better rehabilitation and the mentally retarded people for better learning. This research is first of its kind which evaluates the prevalence of refractive error in mentally retarded and gives subtle data about the number of students with poor vision due to refractive error alone. Methods: The study was cross-sectional and descriptive in nature. The study was carried out among 138 students of 5 to 40 years of age in three different mentally retarded schools of Kathmandu valley using convenience sampling method. Results: Out of 138 students, 94 were found to have refractive error accounting for 68.12%. In males, number of cases with refractive error was high in the age group of 6-10 years and 11-15 years but in females it was in the age group of 11-15 years. Simple hyperopia was the commonest type of refractive error accounting to 50.27% of the total. 20% of the cases had visual impairment. Conclusions: A maximum number of mentally retarded students had vision problems that could have severe impact on their education, training and daily living activities. Thus regular vision screening should be carried out in the schools for mentally retarded. Keywords: mentally retarded; prevalence; refractive error; visual disabilities; visual impairment.