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Editors Selection IGR 10-3
Pseudoexfoliation
Comment by Anastasios Konstas on:
13373 Glaucomatous damage in normotensive fellow eyes of patients with unilateral hypertensive pseudoexfoliation glaucoma: normotensive pseudoexfoliation glaucoma?, Yarangumeli A; Davutluoglu B; Koz OG et al., Clinical and Experimental Ophthalmology, 2006; 34: 15-19
In this retrospective study, Yarangumeli et al. (165) have investigated the prevalence of glaucomatous damage in the normotensive eye of patients with unilateral exfoliative glaucoma (XFG). In their review of charts from 111 patients with unilateral XFG they report a significant incidence of glaucomatous damage (40%) in the 'normotensive' contralateral eye. Low tension is generally rare in XFG. Sadly, the research design employed in the present
investigation does not allow a great degree of certainty that in all their cases the fellow eye was indeed normotensive.with the IOP at all times below 21 mmHg as the authors suggest. It is worth highlighting that the mean IOP in the eyes with clinically apparent XFG at diagnosis was 34.0 mmHg, which is in keeping with the standard clinical presentation of patients with XFG. The authors do not clearly state if all patients underwent a diurnal assessment at the time of diagnosis or later and what was the impact of the time interval between diagnosis and diurnal evaluation. It is hard to believe that all patients in their unit underwent routive diurnal IOP assessment at the time of diagnosis so clearly some selection has occurred in their cohort. The definition of normotensive eye exfoliation patient relied upon a diurnal curve which was performed between 8:00 and 16:00 hours. This implies as the authors acknowledge themselves that in a proportion of their patients the peak IOP was missed since it might have occurred outside office hours. Furthermore, the authors complicate the interpretation by including all contralateral eyes with or without the clinical evidence of exfoliation material.
Still, an important conclusion derived from the present study is the importance of assessing the IOP in the contralateral eyes of patients with unilateral XFG with more than a few single IOP measurements every few months. This study suggests that significant parameters in assessing the risk of glaucoma development in such eyes are the fluctuation of IOP and the peak pressure. These appear the most important predictors in evaluating the risk of future XFG development. It is worthwhile noting that the glaucomatous group exhibited a diurnal fluctuation of 6.0 mmHg and a peak IOP of 19.0 mmHg, whereas the group with normal visual fields had a fluctuation of 4.2 mmHg and a peak IOP of 15.7 mmHg. It is conceivable of course, that unilateral XFG does not exist and what we really see is a delayed process and asymmetric, but late development of glaucoma in these eyes. What biological factors protect the fellow eye in the presence of severe unilateral XFG remains one of the most intriguing features of the condition. Elucidating these factors may open future research avenues in the prevention of the disease.
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