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Editors Selection IGR 12-1

Comments

Comment by Chris Leung on:

22358 Disc hemorrhages and treatment in the early manifest glaucoma trial, Bengtsson B; Leske MC; Yang Z et al., Ophthalmology, 2008; 115: 2044-2048

See also comment(s) by Don Budenz • Kenji Kashiwagi • James Morgan • Jody Piltz-Seymour • Hidenobu Tanihara • Boel Bengtsson •

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The recent article by Bengtsson et al. from the Early Manifest Glaucoma Trial has contributed to our quest for greater understanding ofdisc hemorrhages. The report from this prospective, randomized longterm trial evaluated the influence of treatment on the development of disc hemorrhages over an average of eight years (maximum 11 years). The authors found that "IOP-reducing treatment was unrelated to the presence or frequency of disc hemorrhages." A few notable features of this study and the conclusions deserve mention.
A remarkably high percentage of patients (55%) were noted to have disc hemorrhages (DHs) in this study. Most prior studies have found that DHs developed in 5-45% of glaucoma patients with the higher percentages occurring in studies of NTG. Most of these prior studies had far fewer evaluations than the EMGT. Since detection will increase with increased assessments, the higher percentage of patients with DH in the EMGT may reflect increased observations. Alternatively, the EMGT population had a mean baseline IOP of less than 21 and the higher DH rate may reflect this large NTG population. A third explanation may be that the population in the EMGT is unique and cannot be generalized to other glaucoma populations.
The authors should be commended for the high rate of detection of DHs on ophthalmoscopy. The OHTS trial found a dismal rate of DH detection ophthalmoscopically, while this EMGT report found that a similarnumber of patients with DHs using ophthalmoscopy or photographs.

With increased surveillance, the EMGT showed that most patients with DHs can be detected ophthalmoscopically

Detecting DHs require close observation and attention, and a specific callout for DHs was included in the EMGT protocol.With increased surveillance, the EMGT showed that most patients with DHs can be detected ophthalmoscopically.
However, photography still detected a significantly greater frequency of disc hemorrhages in the EMGT compared to clinical examination, and remains an important part of glaucoma assessment and follow-up.

The authors were unable to identify any difference in the number of patients with DH between the treated group and untreated group. The number of observations for the two groups was not included. Data were censored after progression, and since a greater number of untreated patients progressed sooner, it is possible there was a difference in the number of observations in the two groups. If there were a greater number of observations in the treated group, more DH could potentially be detected which could artifactually impact the study results.
Further comparisons between treated and untreated groups, stratifying the treated group into different levels of IOP reduction, may have been revealing. Since the treatment arm of the EMGT was not target based, there was a wide variation in the magnitude of IOP lowering; comparisons with stratified treated data may have provided additional information, though the deceasing sample size may have reduced the power to detect differences.
The authors conclude that there is no relationship between IOP lowering therapy and disc hemorrhages. While this may be true, the mean IOP decrease from baseline to all study visits in the EMGT was 22%. Disc hemorrhages were more frequent in eyes with lower IOP, and these eyes had the smallest reduction of IOP with treatment in this study. As was found in Miyake�s study, it is possible that a larger reduction in IOP is required to diminish the frequency of DHs.

With increased surveillance, the EMGT showed that most patients with DHs can be detected ophthalmoscopically

This report clearly stresses the great prognostic significance of disc hemorrhages and offers important contributions to the body of literature on this topic.
However, many of the same key questions remain unanswered since the time Drance reintroduced the ophthalmic community to disc hemorrhages. The relationship between treatment and disc hemorrhages may be answered definitively when we unlock the mystery of their pathogenesis.

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