Prevalence, Causes, and Risk Factors for Functional Low Vision in Nigeria: Results from the National Survey of Blindness and Visual Impairment

Entekume, G; Patel, J; Sivasubramaniam, S; Gilbert, CE; Ezelum, CC; Murthy, GVS; Rabiu, MM; Nigeria Natl Blindness, V; (2011) Prevalence, Causes, and Risk Factors for Functional Low Vision in Nigeria: Results from the National Survey of Blindness and Visual Impairment. Investigative ophthalmology & visual science, 52 (9). pp. 6714-6719. ISSN 0146-0404 DOI:

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PURPOSE. To estimate prevalence and describe causes of functional low vision (FLV) among a nationally representative sample of Nigerian adults, assess socioeconomic risk factors, and estimate the number of adults in Nigeria who might benefit from low vision assessment or rehabilitation services. METHODS. Multistage, stratified, cluster random sampling with probability proportional to size procedures were used to identify a nationally representative sample of 15,027 persons aged 40 years or older. Distance vision was measured using a reduced logMAR tumbling E-chart. All participants with presenting acuity of < 6/12 in one or both eyes had their corrected acuity measured and underwent detailed clinical examination to determine the cause. FLV was defined as best corrected vision < 6/18 in the better eye, after excluding those with no light perception in both eyes and those with treatable causes. Analysis took account of the clustered design. RESULTS. In all, 13,591 individuals were examined in 305 clusters (response rate, 89.9%). The crude prevalence of FLV was 3.5% (95% confidence interval, 3.1-3.9%). This was lower than the prevalence of blindness, which was 4.2%. Glaucoma was the most common cause and age the most important risk factor. There are estimated to be approximately 5000 adults with FLV per million population and 340 who are totally blind. Only 9.3% of those with FLV were of working age and literate. CONCLUSIONS. These are the first data on the prevalence, causes, and risk factors for FLV from Africa. Results support studies from Asia that the prevalence of FLV is lower than previously thought. Because the majority of adults with FLV in Nigeria live in rural areas and are elderly and not literate, further research is required to assess the nature of the interventions required and who might best deliver them. (Invest Ophthalmol Vis Sci. 2011; 52: 6714-6719) DOI: 10.1167/iovs.11-7293

Item Type: Article
Keywords: randomized controlled-trial, eye examination methodology, rehabilitation, services, design, acuity
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Clinical Research
Research Centre: The International Centre for Evidence in Disability
International Centre for Eye Health
Centre for Global Non-Communicable Diseases (NCDs)
PubMed ID: 21775655
Web of Science ID: 294548300045


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