Discovery of cause of disc hemorrhage a pressing need

"A linkage between disc hemorrhage and glaucoma was first noted more than a century ago, but that observation was largely forgotten until the early 1970s, when the association was again brought to the fore by Drance," said Dr. Kitazawa, professor emeritus, Department of Ophthalmology, Gifu University School of Medicine, Gifu, Japan. "Over the past 25 years, a number of studies have provided information about the characteristics of disc hemorrhage and established it as an important risk factor for progression of glaucomatous optic nerve damage, especially in NTG. Nevertheless, the etiology and pathogenesis of disc hemorrhage remain to be clarified, and we still know little, if anything, about how to treat it."

"Disc hemorrhages are transient in nature, but also often recur," he said. "The reported prevalence rate depends on the number of repeat exams and the length of follow-up. According to some estimates, the frequency of disc hemorrhage in NTG may range between 38% and 70%."

Most disc hemorrhages are linear, and they may be seen at virtually any location. Most are found in the inferotemporal or superotemporal sectors, however, he said.

"Results of one population study showed 87% of disc hemorrhages were located either inferotemporally or superotemporally, regardless of the absence or presence of glaucoma, and that finding is consistent with a number of previous reports. However, in glaucomatous eyes, disc hemorrhages are most commonly seen close to the border between localized retinal nerve fiber layer (RNFL) defects and relatively healthy-looking RNFL," Dr. Kitazawa said.

The importance of disc hemorrhage as a negative prognostic factor for glaucoma was identified in the Collaborative Normal-Tension Glaucoma Study (CNTGS) and other trials, including a study conducted by Dr. Kitazawa and colleagues.

"We demonstrated that among eyes with NTG, the risk of visual field progression was 3.6-fold higher in eyes with disc hemorrhage versus those without," he said. "Furthermore, during 6.5 years of follow-up, visual field loss progressed in 100% of eyes with recurrent disc hemorrhages compared with only 58% of those without recurrence."