Period prevalence and incidence of optic disc haemorrhage in normal tension glaucoma and primary open-angle glaucoma

Background: To investigate and compare the period prevalences and incidences of optic disc haemorrhages in normal tension glaucoma and primary open-angle glaucoma. Design: Hospital-based retrospective study. Participants: Four hundred and four patients normal tension glaucoma and 210 patients primary open-angle glaucoma that underwent with with consecutive disc examinations at least quarterly for at least 1 year and stereoscopic optic disc photographs at intervals of 6 to 12 months between 1992 and 2007. Methods: The period prevalence of disc haemorrhages, gender predominance among patients with disc haemorrhage, and cumulative incidence of normal tension glaucoma and primary open-angle glaucoma were compared. Main Outcome Measures: Period prevalence, cumulative incidence, and gender predominance of DHs in patients with NTG and POAG. Results: Three hundred and eighty-seven patients (387 eyes) of normal tension glaucoma patients and 205 patients (205 eyes) of primary open-angle glaucoma patients were finally enrolled in the study. The period prevalence and incidence rates of the stereoscopic optic disc photograph-confirmed glaucomatous disc haemorrhages were 33.3% (129/387), 0.46 +/- 0.18 times/year in the normal tension glaucoma group, and 17.6% (36/205), 0.34 +/- 0.23 times/year in the primary open-angle glaucoma group, respectively. The absolute values and ratios of primary open-angle glaucoma and normal tension glaucoma in period prevalences and incidence rates in the present study were higher than in previous studies. No significant difference in gender ratios was found between patients that did or did not develop disc haemorrhage for both types of open-angle glaucoma (P > 0.05, respectively). Conclusions: The primary open-angle glaucoma group had higher period prevalences and incidence rates of disc haemorrhage than those reported previously. Disc haemorrhages were found to develop independent of gender.