We would like to thank Dr Teus for his interest in and comments on our article, entitled “Increased likelihood of glaucoma at the same screening intraocular pressure in subjects with pseudoexfoliation: the Thessaloniki Eye Study.” We agree with Dr Teus that population-based data on pseudoexfoliation (PEX) and pseudoexfoliative glaucoma (PEXG) are limited and therefore needed. In our opinion, the considerably high prevalence of PEX and PEXG found in the Thessaloniki Eye Study (TES) provides a dataset suitable for comparison of clinical characteristics between primary open-angle glaucoma (POAG) and PEXG. In the present manuscript we reported that for intraocular pressure (IOP) level > 20 mm Hg, the proportion with glaucoma increased highly in subjects both with and without PEX, while it was much higher among those with PEX at the same screening IOP. This may be attributable to the reported higher IOP fluctuations in eyes with PEX or to greater susceptibility to high IOP in the optic nerves of eyes with PEX.
In this context, it is very interesting that the study by Teus and associates evaluating the correlation between IOP and the amount of visual field loss suggests that vulnerability of the optic nerve to increased IOP may be different between POAG and PEXG. This is an important contribution to the literature and we apologize for not citing it in our manuscript.
Although the 2 studies have different outcome measures as described above, the conclusions that may be drawn from their findings share a common point, which is the potential of greater susceptibility of the optic nerve to high IOP in subjects with PEX. However, we need to note that in the study by Teus and associates only subjects with IOP > 21 mm Hg were included. Our study included unbiased randomly selected cases from the general population, providing the whole spectrum of IOP. In addition, the cutoff value of 20 mm Hg was determined based on a statistical analysis estimating the threshold IOP level above which the proportion with glaucoma increased statistically significantly among both PEX and non-PEX subjects. As reported in our manuscript, the results were different for IOP > 20 mm Hg compared to IOP ≤ 20 mm Hg. Interestingly, for IOP ≤ 20 mm Hg, the proportion with glaucoma did not differ between PEX and non-PEX subjects.