Short-term fluctuation of intraocular pressure is higher in patients with pseudoexfoliation syndrome despite similar mean intraocular pressure: a retrospective case-control study

Higher levels of short-term fluctuation of intraocular pressure (IOP) are characteristic of pseudoexfoliation syndrome (PEX). However, it is not known whether they are just a side effect of the higher mean intraocular pressure (IOP) or an independent feature. The purpose of this study was to compare short-term fluctuation of IOP between eyes with PEX and control eyes that were matched as closely as possible for mean IOP. In this retrospective case-control study, all patients with confirmed PEX were identified from the database of the Erlangen Glaucoma Registry. From the same database, matched control eyes with similar treatment, age, glaucoma stage, and mean IOP were identified. For each patient, data from multiple extended diurnal IOP profiles were available. Seventy-eight eyes were included in the study (39 with PEX and 39 matched control eyes). Although a very close match was achieved, a small but statistically significant difference in mean IOP was still present, but this did not seem to explain the differences in IOP fluctuation levels. Eyes with PEX had significantly higher short-term IOP fluctuations (SD of IOP and range of IOP). The higher levels of short-term fluctuation in IOP appear to be an independent feature of PEX and not merely a secondary effect of the higher mean IOP. We suggest that this may have practical implications, even if IOP fluctuation levels should not prove to be an independent risk factor for development/progression of glaucoma, because more frequent measurements are needed in these patients to obtain good estimates of mean IOP and changes in IOP under treatment.