Over the past few decades, there has been a wealth of investigations on the prevalence of open-angle glaucoma (OAG) but less so on its incidence, as few population-based studies worldwide have re-examined their original cohorts to determine how these patients fared over the long run. Recently released findings from the second phase of the Thessaloniki Eye Study found that the 12-year rate of OAG was similar or sometimes higher compared with other Caucasian populations but that glaucoma was three-times more likely in individuals who also had pseudoexfoliation (PEX) syndrome.

 Considered to be the most common type of secondary glaucoma and typically associated with high intraocular pressure (IOP), PEX is more aggressive in its course and more resistant to medical treatment than OAG, the researchers said. Although PEX is an established risk factor for the prevalence, incidence and progression of glaucoma, the majority of people with PEX don’t have the eye disease, which suggests that the precise interaction between the two conditions is unclear, the authors explained.

The investigation, which included a predominantly elderly Caucasian population, had previously found that the prevalence of PEX in Greece was 11.9% in those aged 60 or older, which is higher than other parts of the world, including the United States.

The 12-year follow-up to the original investigation included the surviving cohort, or 1,092 of 1,468 eligible subjects. The participants were an average of 69 years old.

Key study highlights included:

• The 12-year incidence of OAG was 4.4%, or 0.37% per year.

• In the overall population, the incidences of OAG and PEX glaucoma were 2.1% and 2.3%, respectively.

• The corresponding incidence proportions were 2.9 in those without PEX and 8.9 in those with PEX at baseline and/or incidence. The researchers found the latter to be strongly associated with higher odds for incident glaucoma.

• Of all OAG cases, about 11% had a baseline IOP greater than 21mm Hg.

In the vast majority of cases with incident OAG, baseline IOP was within the normal range. However, a substantial number of study participants with normal IOP at baseline and incident glaucoma developed elevated IOP between the two phases of the study. These findings have important clinical implications for case detection in the community, including the monitoring of individuals with PEX, with or without elevated IOP, the authors noted.