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In this study by Bengtsson et al., the investigators reviewed photographs and clinical investigators� determination of optic disc hemorrhages throughout the course of the Early Manifest Glaucoma Trial. The specific scientific question was to determine whether IOP lowering affected the incidence of disc hemorrhages. They found that the group that received IOP lowering therapy in the form of betaxolol and laser trabeculoplasty had the same incidence of disc hemorrhage as those that were observed. Just over one half of all subjects (140/255) had disc hemorrhages during follow-up and the percentage was the same in the treatment and observation groups. Patients with disc hemorrhages had, on average, a shorter time to progression of glaucoma, suggesting that disc hemorrhages are a predictor of progression, but the level of IOP was not related to occurrence of disc hemorrhage. The authors suggest that disc hemorrhages are not indicative of inadequate IOP lowering and confirm that the evidence is rather week that observation of a disc hemorrhage in patients with glaucoma should prompt more aggressive treatment.
Disc hemorrhages are not necessarily in the causal pathway of IOP resulting in glaucoma, but are an associated sign of, perhaps, some other causative factor
This is an important contribution to the literature, because it is a large prospective study that affects clinical practice. It is well known that the occurrence of a disc hemorrhage portends the progression of glaucoma. The clinician is naturally going to advance therapy, which may very well slow the progression of glaucoma, but does not decrease the likelihood of optic disc hemorrhages from occurring in the future. In some way, disc hemorrhages, then, are a sign of progression of glaucoma, but not directly related to the level of IOP, and they are not in the causal pathway of IOP resulting in glaucoma, but are an associated sign of, perhaps, some other causative factor as yet unidentified.