Abstract
Purpose: :
To assess the prevalence of refractive error and visual impairment in school aged children in Ghana, West Africa.
Methods: :
Random selection of geographically defined clusters was used to identify a sample of children aged 12 - 15 years in the Ashanti region. From February to September 2009, children in 60 clusters were enumerated through a class to class survey and examined in classrooms. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia and examination of anterior segment, media and fundus. In seven clusters, children with reduced vision and a sample of those with normal vision underwent independent replication examination for quality assurance.
Results: :
A total of 2455 children from 53 private schools were enumerated, and 2436 (99.2%) were examined. The prevalence of uncorrected, presenting, and best visual acuity of 20/40 or worse in the better eye was 3.7%, 3.5% and 0.37% respectively. Refractive error was the cause in 69.4% of 157 eyes with reduced vision, Amblyopia in 12.7%, retinal disorders in 5.7%, corneal opacity in 4.5%. Other causes were presented in 0.64% and unexplained causes were present in the remaining 6.4%. Exterior and Anterior segment abnormalities were observed in 43 (1.8%) of children, mainly corneal and conjunctiva. Myopia (at least -0.50D) in one or both eyes was present in 3.2% of children when measured with retinoscopy and in 3.4% measured with autorefraction. Hyperopia (+2.00D or more) in at least one eye was present in 0.4% of children when compared with retinoscopy and in 0.4% measured with autorefraction, with no significant predictors of hyperopia risk.
Conclusions: :
Prevalence of reduced vision is comparatively low in school age African children in Ghana, most of it due to uncorrected refractive error. Over 90% of children with significant refractive error do not have necessary corrective spectacles. Effective strategies are required to provide access to refractive services. The high prevalence of corneal and other anterior segment abnormalities is also a reflection of the inadequacy and inaccessibility of primary eye care services in this area.
Keywords: refraction • visual impairment: neuro-ophthalmological disease • spectacle lens