Prevalence and Causes of Visual Impairment Among Adult Patients Seen at Scottish Livingstone Hospital Eye Clinic, Molepolole, Botswana

Abstract

Background: Distant visual impairment represents mild sight impairment, with a visual acuity worse than 6/12 in the better seeing eye. This is further divided into mild, moderate, severe, and blindness. Globally, over 2.2 million people have impaired vision, with nearly half being affected by preventable or treatable causes. The growing number of people living with visual impairment has made the issue a public health priority, with prevention being of paramount significance. Study objective: The primary objective of this study was to determine the prevalence and factors that contribute to visual impairment in adult patients who visit the Scottish Livingstone Hospital (SLH) eye clinic in Botswana. Materials and methods: A cross-sectional hospital-based study was conducted from 3rd January to 31st January 2024. The study was done in Scottish Livingstone Hospital, Molepolole, Botswana. Using the Shaeffer formula, a sample size of 319 was calculated. The participants were selected with consecutive sampling. All the participants who were included signed an informed, then a questionnaire guided interview was conducted. The participants with visual impairment were examined, and diagnosis of the cause was made and appropriate management ensued. Visual acuity was classified using the International Classification of Diseases 11th edition. Data analysis was done using the SPSS version 26. Results: Visual impairment prevalence was at 49.2% (95%CI 42.6 - 55.8%). 67% of the visual impairment participants were females, more that 50% were aged 70 years or older and 88% resided in villages. Cataract was the leading trigger for visual impairment (42.7%) followed by glaucoma (26.8%) and refractive errors (18.5%). Less common causes of visual impairment were found to be keratoconus (3.2%), optic neuropathy (1.3%) and diabetic macula oedema (0.6%). Discussion: Visual impairment was noted to increase with age. More females were affected than males, those with no formal education background and those from low socio-economic backgrounds had higher prevalence visual impairment. Visual impairment often resulted from cataracts, followed by glaucoma and refractive errors. Conclusion: At the time of the study, a significant burden of visual impairment was observed at Scottish Livingstone Hospital, largely due to treatable or preventable causes. However, a considerable percentage of cases involved irreversible causes of visual impairment.