Diabetes and visual impairment in sub-Saharan Africa: evidence from Cameroon

BACKGROUND "Vision 2020 - the right to sight" is a program which purpose is to eliminate avoidable blindness by the year 2020 through the implementation of concrete action plans at the national and district levels. Accordingly, baseline data are needed for the planning, monitoring, follow-up and evaluation of this program. The present study aimed to better characterize visual impairment and blindness in Cameroonian diabetics by providing with baseline data on the prevalence and main causes of these affections. METHODS This was a hospital-based cross-sectional study, conducted from October 2004 to October 2006 at the Department of Ophthalmology of the Douala General Hospital, Cameroon. We included 407 diabetic patients who were referred from diabetes clinics for ophthalmologic evaluation. Ophthalmologic data included visual acuity, intra-ocular pressure, fundoscopy and fluorescein angiography. RESULTS The prevalence of blindness and poor vision were respectively 12.3% and 17.4% with regard to the worst eyes. Fifty nine (14.5%) patients were found with diabetic maculopathy, of whom 25.4% (15/59) had poor vision, and 25.4% (15/59) were blind. The prevalence of sight threatening retinopathy (severe non-proliferative and proliferative) was 17.4%. The degree of visual impairment was comparable in both diabetic types (p = 0.825), and it increased with the severity of retinopathy (p < 0.0001), as well as that of maculopathy (p <0.0001). The prevalence of glaucoma was 15% (61/407) when considering the worst eyes. The severity of visual impairment increased with the severity of glaucoma (p = 0.001). One hundred and twenty-one (29.7%) patients presented with cataract irrespective of its location or severity. Cataract was significantly associated with poor vision and blindness (p < 0.0001). Hypertensive retinopathy (4.9%), papillary ischaemia (2.7%), vaso-occlusive eye disease (2.5%), and age-related macular edema (2%) were the other potential causes of visual impairment and blindness encountered the most in our setting. Age ≥ 50 years, male sex, duration of diabetes and hypertension variously increased the risk of having glaucoma, cataract, diabetic retinopathy or maculopathy. CONCLUSION Poor vision and blindness are frequent in Cameroonian diabetics, and their causes are similar to those reported by various other surveys: mainly cataract, glaucoma, diabetic retinopathy and maculopathy.