Prevalence of visual problems in a rural population of Kenya

Abstract

Dear editor, The poverty that is present in low-income countries has drastic consequences for blindness, visual impairment and general eye care services. Despite containing 10% of the world’s population, Africa accounts for 19% of the global blindness with an incidence of more than 1% (Naidoo 2007). Kenya is an African country of low development, with a human development index of 0.47. In this country, we have recently conducted a massive campaign of refractive error assessment in the context of international cooperation that has allowed us to study the prevalence of refractive errors and blindness associated with this factor in large sample of population. A total of 326 people attending for eye examination in April 2011 in the area of Voi and Buguta in South Kenya were examined. Mean age was 43.0 (SD: 19.3) years, with 53.1% women. LogMAR uncorrected visual acuity (UCVA) at distance was found to range from −0.08 to 1.30, with a mean value of 0.17 (SD: 0.25). Refraction was obtained in a total of 100 eyes because of the significant limitation in UCVA (≥0.3 LogMAR). Table 1 summarizes the mean refractive outcomes obtained. The percentage of refracted eyes with myopia, defined as an SE of −0.50 D or more negative, was 58%. The percentage of refracted eyes with hyperopia defined as an SE of +0.5 D or greater was 30%, while the percentage of hyperopia defined as an SE of +2.00 D or greater was 4% (Fig. 1). Distribution of the spherical equivalent in the 100 eyes in which spherocylindrical refraction was obtained. The main pathological conditions that were detected were as follows: cataract (14 patients, 4.3%), corneal leukoma (2 patients, 0.6%), ocular trauma (6 patients, 1.9%), exotropia (1 patient, 0.3%), glaucoma (3 patients, 0.9%) and conjunctivitis (4 patients, 1.2%). Pseudophakia was present in a total of 18 patients (5.5%). The prevalence of blindness (1.3%) and visual impairment (6.3%) found (Table 2) was similar than that reported in Kibera slums of Nairobi (0.6% and 6.2%) (Ndegwa et al. 2006) as well as than that reported in the Nakuru district (2% and 5.8%, respectively) (Mathenge et al. 2007). Therefore, our results are consistent with the previous scientific evidence. The incidence of refractive error as a cause of visual impairment was higher than that caused by cataract, but percentages were smaller (21.6% and 8.1%, respectively) than those reported in the previous mentioned studies. This suggests a greater coverage of vision services in the area analysed compared to other regions evaluated previously. One factor accounting for this may be the increasing number of campaigns for the prevention of blindness carried out in rural Kenya in the recent years. In this campaign, prescription was provided in a total of 181 patients (55.5%), sunglasses in 29 patients (8.9%) and artificial tears in 12 patients (3.7%). From the total of prescription glasses provided, 137 were for the correction of presbyopia (75.69%). It should be considered that presbyopia is the most common spectacle requirement in low-income regions, and the unmet need for presbyopic spectacles in these regions is very high (Sherwin et al. 2008). In conclusion, the main cause of visual impairment is the presence of refractive error followed by cataract. Both causes are avoidable with a correct clinical management. This suggests that there is still a need of implementation of the eye care service in this region in spite of existing lower rates of visual impairment in comparison with other African countries. We thank the MATH-Kenya (Embracing the World) for their support in the campaign.