Evaluating the effectiveness of opportunistic eye screening model for people with Diabetes attending Diabetes clinic at Mnazi Mmoja hospital, Zanzibar

Background: Diabetes and its related microvascular complications like Diabetic retinopathy are showing an alarming rise in developing countries like Zanzibar. Objective of the present study is to evaluate the impact of integrating eye screening for all subjects attending the diabetes clinic at Mnazi Mmoja Hospital in Zanzibar and to estimate the prevalence of visual impairment and diabetic retinopathy among the subjects. Methods: This is a cross sectional study involving 356 randomly selected patients who had attended the diabetes clinic between July and August 2012. All subjects underwent comprehensive eye examination including fundus evaluation after dilatation by a cataract surgeon and an ophthalmologist, independently. Data was collected using the designated questionnaire and analysed using the SPSS software. Blindness and visual impairment was defined as presenting VA <3/60 and <6/18 to 6/60 in the better eye respectively and DR was graded using the International classification of Diabetic Retinopathy severity grading scale. Results: A total of 356/967 subjects were recruited in a duration of 2 months; 176 (49.4%) were male and the mean age was 52.21 (SD 15.3). Targeted eye screening of diabetics showed that 231/356 (65%) of the subjects had eye problems, including potentially blinding conditions that required immediate intervention in contrast to the existing self reported referral where only 10% of an average of 200 diabetics underwent eye checkup in a year. The prevalence of visual impairment was 20.2%; 95% CI: 16.4-24.7 and blindness in 9.3%; 95% CI: 6.7-12.7. The prevalence of DR was 28.3% and sight-threatening DR was reported in 9%. Among the DR cases, 30% had sight threatening DR including 28% macular edema, 2% severe NPDR and PDR. Multivariate analysis showed a higher risk for any DR in older subjects >50 years (OR: 2.19; 95% CI: 1.14 - 4.25) and in females (OR: 1.92; 95% CI: 1.07 - 3.44). Conclusion: Opportunistic DR screening model achieved higher yield of identification of visual impairment and DR compared to the yield of 10% of existing self reported Diabetic eye screening model at Zanzibar. Integration of eye screening at diabetes clinics helps in early identification and provision of appropriate treatment for reducing blindness due to diabetes.