Rapid assessment of avoidable blindness and diabetic retinopathy in individuals aged 50 years or older in Costa Rica

In the present study, we examined the causes and the prevalence of avoidable blindness and visual impairment, as well as the prevalence of diabetic retinopathy in individuals aged ≥50 years in Costa Rica, in order to provide baseline data for the initial planning and monitoring of ongoing blindness intervention programs. The assessment was based on the standardized methodology of the Rapid Assessment of Avoidable Blindness and Diabetic Retinopathy, a population-based survey for blindness and visual impairment. From 3,255 eligible subjects, 76.6% were examined. The adjusted prevalence of bilateral blindness [presenting visual acuity (VA) in the better eye of less than 3/60] was 1.7% (95% confidence interval, 1.2%–2.2%), with avoidable causes (treatable and preventable) accounting for 68.8% of cases. The main causes of blindness were cataract (52.1%), glaucoma (6.3%), and diabetic retinopathy (6.3%); these data were similar to those for other neighboring countries. Cataract surgical coverage (CSC) in the survey area was estimated as 88.9% for individuals with blindness (VA, <3/60), 76.6% for those with a VA of <6/60, and 60.3% for those with a VA of <6/18. The most common barriers against cataract surgery in individuals with a best-corrected VA of ≤6/60 included “need not felt” (48.8%) and “fear” (14.6%). Among individuals with a past history of cataract surgery, only 57.1% showed a “good” or “very good” outcome (VA, ≥6/18). Finally, 23.5% individuals with known or newly diagnosed diabetes showed retinopathy and/or maculopathy, with 6.2% exhibiting sight-threatening diabetic retinopathy (proliferative retinopathy, referable maculopathy, or both). Our findings indicate the need to overcome barriers against surgery for cataract, which is the main cause of avoidable blindness, to increase CSC, and to improve surgical outcomes. Moreover, improved methods for diabetic retinopathy screening can ensure prompt identification of patients with a risk of blindness. Glaucoma screening is also necessary for areas with a high prevalence.