The additional yield of screening for open-angle glaucoma in a population with high prevalence of pseudoexfoliation: The Thessaloniki Eye Study

To identify incident open-angle glaucoma (OAG) cases detected through regular ophthalmic care and from screening in a population-based cohort and study the additional yield of screening in a population with high prevalence of pseudoexfoliation (PEX).

Longitudinal, population-based study in Thessaloniki, Greece. Among eligible subjects, 1092 were examined at the follow-up stage. Previously undiagnosed glaucoma was defined as the absence of prior self-reported glaucoma or ocular hypertension or prior medical/surgical treatment. Glaucoma severity was assessed using the Hodapp-Parrish-Anderson criteria.

The population at risk, after excluding glaucoma patients diagnosed at baseline, consisted of 1042 participants. Forty-six subjects developed incident OAG and 27 of them (58.7%, 95% CI: 43.5-71.7) were undiagnosed at follow-up visit, corresponding to a 2.6% (95% CI: 1.6-3.6) 12-year incidence rate of undiagnosed OAG. After stratification, the incidence of undiagnosed OAG was 1.8% in non-PEX subjects (14 of 772) and 4.8% in PEX subjects (13 of 270). Glaucoma stage did not differ significantly between previously diagnosed and undiagnosed cases (p = 0.46 for better eye and p = 0.72 for worse eye). Among undiagnosed cases, 7 had moderate or worse visual field loss in both eyes, and 17 in at least one eye.

The overall rate of undiagnosed incident OAG in this population-based cohort was substantial. A screening programme could have detected a significant number of glaucoma cases. The high rates of undiagnosed glaucoma among PEX subjects could suggest a higher additional yield of screening in this group. More studies are needed to evaluate the cost-effectiveness of screening in populations with high PEX prevalence.