AVOID PRECONCEPTIONS

Many common preconceptions regarding pseudoexfoliation and pseudoexfoliative glaucoma find little support in the findings of population studies, said Fotis Topouzis MD, Aristotle University Thessaloniki, Greece, at a Glaucoma Day session at the XXXII Congress of the ESCRS in London.

He noted that many of these false preconceptions paint a somewhat grimmer clinical picture of pseudoexfoliation than is actually the case, depicting the condition as typically taking an aggressively glaucomatous course, often undiagnosed, with poorly controlled intraocular pressure (IOP) and rapid disease progression.

In fact, current evidence indicates that only a minority of pseudoexfoliation patients have glaucoma and that, when pseudoexfoliative glaucoma occurs it is less likely than primary open-angle glaucoma to remain undiagnosed.

Although pseudoexfoliative glaucoma is more aggressive with more rapid progression and often poorly controlled at the individual patient level, this is counter-balanced at the population level by the fact that less pseudoexfoliative glaucoma cases remain undiagnosed and untreated, resulting in similar mean visual field defect between pseudoexfoliative and primary open-angle glaucoma cases in the community.

In the Thessaloniki Eye Study, the prevalence of all types of open-angle glaucoma among those over 60 years of age was 5.5 per cent. The prevalence of primary open-angle glaucoma was 3.8 per cent and the prevalence of pseudoexfoliative glaucoma with 1.7 per cent. Meanwhile, the prevalence of pseudoexfoliation was 11.9 per cent in the Greek population, and among those patients the prevalence of glaucoma was 15.2 per cent.

“Despite the high prevalence of pseudoexfoliation in the Greek population, the prevalence of primary open-angle glaucoma appears to be twice that of pseudoexfoliation glaucoma, and 85 per cent of patients with pseudoexfoliation don’t have glaucoma," Dr Topouzis said.

Those figures were closely paralleled by the findings of the Blue Mountain Eye study in Australia, where the prevalence of primary open-angle glaucoma among those older than 60 years was only slightly lower ( 3.5 per cent). Although the prevalence of pseudoexfoliation (2.3 per cent) and pseudoexfoliative glaucoma (0.5 per cent) were lower, the prevalence of glaucoma among eyes with pseudoexfoliation was roughly the same (14.2 per cent).

Undiagnosed cases

The Thessaloniki Eye Study also showed that the rate of undiagnosed cases was 57.1 per cent in primary open-angle glaucoma patients, compared to 34.9 per cent in patients with pseudoexfoliative glaucoma. Primary open-angle glaucoma patients had three to four times increased risk to be undiagnosed compared to patients with pseudoexfoliative glaucoma after adjusting for potential confounders.

The likelihood of glaucoma increased highly in both pseudoexfoliation and non-pseudoexfoliation subjects for IOP >20mmHg, although the likelihood was approximately three times higher among those with pseudoexfoliation at any IOP above 20mmHg, an indication that pseudoexfoliation glaucoma involves additional contributing factors apart from IOP.

However, when all patients treated and untreated were considered, the difference between the mean IOP of the two groups was no longer significant. There were no significant differences between the two groups regarding the cup disk ratio or the visual field AGIS (Advanced Glaucoma Intervention Study) score whether or not they were treated. These findings reflect the fact that less pseudoexfoliative glaucoma cases remain undiagnosed and untreated.

He added that, unlike the Blue Mountain Eye Study, in the Thessaloniki Eye Study vascular diseases and their treatment were associated only with primary open-angle glaucoma. The Greek study could show no significant associations between pseudoexfoliation or pseudoexfoliative glaucoma and cardiovascular disease, heart attack, coronary artery bypass or vascular surgery.

Therefore the association of pseudoexfoliation or pseudoexfoliative glaucoma with vascular diseases is still under debate and further research is needed to clarify this issue.

Fotis Topouzis: ftopouzis@otenet.gr