Opportunistic Glaucoma Detection in a Diabetic Eye Screening Program: Yield and Feasibility in a Caribbean Population

Purpose: Glaucoma is a leading cause of irreversible blindness worldwide and is highly prevalent in the Caribbean nations. It can remain asymptomatic until the late stages, underpinning the need for screening for early diagnosis. This study aimed to determine whether glaucoma screening should be performed in combination with population-based diabetic retinopathy screening in Trinidad and Tobago. Methods: Diabetic retinopathy screening, including colour fundus photography, was conducted in communities across Trinidad and Tobago. Patients whose fundus photographs met the glaucoma suspect criteria (vertical cup-to-disc ratio (VCDR) ≥ 0.6, VCDR difference ≥ 0.2 between the eyes, disc haemorrhage, or suspected RNFL defect) were referred to the clinic for full evaluation and diagnosis. Results: A total of 1754 adults with diabetes were screened, with 167 patients (9.5%) meeting the glaucoma suspect criteria. 45 patients (26.9% of those meeting the glaucoma suspect criteria) presented to the clinic and underwent a full evaluation. The extrapolated estimated prevalence of glaucoma in the diabetic population was 5.9% (minimum confirmed prevalence 1.6%) and the extrapolated estimated prevalence of undetected glaucoma 2.1%. The positive predictive value of fundus photography for detecting glaucoma was 62.2%. Conclusion: Opportunistic glaucoma screening using fundus photography within an existing diabetic eye screening programme identified a clinically meaningful number of glaucoma cases in this Caribbean diabetic population. Keywords: glaucoma screening, diabetic retinopathy screening, fundus photography, glaucoma prevalence, Caribbean population