RESUMO
OBJECTIVE: The aim of this study is to determine usefulness, validity of retinographies performed in Primary Care as a tool for early diagnosis of open-angle chronic glaucoma (OAG). DESIGN: An observational, descriptive and cross-sectional study with two blinded parallel observers: 2 general practitioners and 1 ophthalmologist. LOCATION: Urban Primary Care Health Centre, and the Ophthalmology Department outpatient clinic. PARTICIPANTS: A total of 196 patients of both genders, between 40-70years, with diabetes and hypertension, and undiagnosed with glaucoma, were recruited by phone call after checking patient lists. Two patients that did not arrive for their appointments for the ophthalmology tests were considered as losses. MEASUREMENTS: For the quantitative diagnostic variable of glaucoma: Accuracy calculated from the sensitivity and specificity, safety from the positive and negative predictive values and the positive and negative probability ratio; interobserver concordance by Kappa index ratio and the intraclass correlation (IC). RESULTS: The retinography for OAG screening has a sensitivity of 21% (95%CI: 0-43%), a specificity of 93% (95%CI: 89-97%), a negative predictive value of 94% (95%CI: 90-97%), and positive of 20% (95%CI: 0-40%); positive probability ratio of 3.07 (95%CI: 0.98-9.62) and negative 0.84 (95%CI: 0.64-1.11). The IC was 0.653 (95%CI: 0.495-0.769) and kappa index of 0.140 (0.106ET). CONCLUSIONS: According to this proposed model, retinography is not a useful tool for the early diagnosis of OAG in Primary Care, as it is not safe enough. Before it can be used, it would need adjustments for its low sensitivity, and the use other combined tests. The training of general practitioners would also need to be improved.