Prevalence and causes of visual impairment amongst hearing impaired school-going children in sub-Saharan Africa: a scoping review

Background: Learners living with hearing impairment are at a higher risk of visual impairment. Purpose: To summarise relevant literature investigating the prevalence and causes of visual impairment amongst learners living with hearing impairment in sub-Saharan Africa. Methods: A search of nine databases and the reference lists of retrieved studies were conducted using the standard methodology for scoping reviews as described in the PRISMA statement. The databases were MEDLINE, PubMed, EMBASE, the Cochrane Library, Global Health, OVID, Google Scholar, Web of Science, and Science Direct. A scoping review of articles published in the English language from 2000 to 2020 was conducted while considering the study design, sub-Saharan Africa, and school for the deaf. Descriptive statistics was used to analyse the data. Results: The initial search retrieved eight studies, seven of which met the set inclusion criteria. All seven studies included employed a cross-sectional design. The prevalence of visual impairment ranged from 2.2-34.6% with the major cause being un-corrected refractive error (7.9-73.26%). The most common type of refractive error was myopia (42.2%) followed by hyperopia (28.6%) and astigmatism (28.6%). Conclusion: This review has demonstrated that there is a paucity of high-quality and well-designed studies that have investigated the prevalence and causes of visual impairment amongst hearing-impaired children in sub-Saharan Africa suggesting the need for further research in this area.