Rapid assessment of avoidable blindness including diabetic retinopathy in Queretaro, Mexico

Abstract

Objective: To determine the prevalence and causes of blindness and visual impairment and the prevalence of diabetes and diabetic retinopathy (DR) in the state of Queretaro, Mexico. Materials and Methods: 180 clusters of 35 people aged ≥ 50 years were randomly selected. Participants had their visual acuity measured and lens examined and had a random blood glucose test to assess their diabetes status. Participants with diabetes had a dilated fundus examination and digital fundus photographs taken. DR was graded using the Scottish DR grading system. Results: The prevalence of blindness among the 5,935 survey participants was 1.0% (95% confidence interval [CI]: 0.7-1.2%). The sample prevalence of severe, moderate, and early visual impairment and functional low vision were 1.6, 3.2, 12.7, and 1.4%, respectively. The most common cause of blindness was cataract representing 29.8% of the cases, followed by DR (17.5%). The most common cause of functional low vision was DR (32.9%). There were 1,115 participants with diabetes (18.8%; 95% CI: 17.4-20.2%), 92 of whom were newly diagnosed during this study. The prevalence of retinopathy and/or maculopathy among these patients was 22.5% (95% CI: 19.0-26.1%), and 3.6% (95% CI: 2.4-4.8%) had sight- threatening DR. Conclusion: Although cataract is the primary cause of blindness among people aged ≥ 50 years in Queretaro, Mexico, DR is the second cause of blindness and the leading cause of functional low vision. There is a need to expand and improve eye care services in Queretaro and to ensure early diagnosis and treatment of diabetes and DR.