Refractive error blindness in Yenagoa, Bayelsa state, Nigeria: a hospital based study

Background: Despite the priority attention giving to refractive error in vision 2020 programme, blindness due to uncorrected refractive error is relatively unexplored. The aim of this study is to determine the prevalence and causes of refractive error blindness in Yenagoa. Method: All consecutive patients presenting to our eye clinic that were diagnosed to have refractive error over a one year period was studied. They underwent a full ocular examination including anterior and posterior segment examination, objective and subjective refraction. Objective refraction was done using a Carl Zeiss 599R autorefractometer. Information obtained included their age, sex, occupation, presenting visual acuity, history of couching and that of cataract surgery without an implant. Statistical analysis was done manually using a scientific calculator. Results: 1168 patients was seen during the study period and 135 persons had refractive error. Of the number with refractive error, 63 were males while 72 were females (M:F=1:1.4). Their age ranged from 6 to 83 years with a mean of 35.7 years (SD±4.102). The prevalence of refractive error blindness was 0.68 %. High myopia accounted for 75% of the blindness while high hyperopia and aphakia accounted for 12.5% each respectively. The prevalence of low vision due to refractive error was 2.5%. Myopia was responsible for half of the cases of low vision while hyperopia and astigmatism accounted for 30% and 16% respectively. Aphakia was responsible for 3.3% of low vision seen. Conclusion: Uncorrected refractive error is potentially blinding with a prevalence of 0.68% in this population, myopia being responsible for majority of cases. Health education is needed to create awareness on the availability of refractive error services in this population in order to stem the tide of needless blindness.