What can we learn from the disc appearance about the risk factors in glaucoma?

The author has been involved in 3 studies, the multicentre collaborative normal-tension glaucoma study, a study of 4 phenotypes of glaucomatous disc appearances and their associations, and a study reporting on biostatistical evidence for 2 distinct chronic open-angle glaucoma populations. These studies have some common threads whose clinical implications are discussed.

Some clinical implications of the collaborative normal tension glaucoma study.

This is to present the results of randomized multicenter normal tension glaucoma study. The primary aim of the study was to establish whether a 30% or greater pressure reduction altered the course of NTG compared to untreated controls. Our study confirms that in glaucoma patients even with normal intraocular pressures the pressure is involved in its pathogenesis and that pressure reduction favourably affects its course in a significant proportion of cases. Moreover, it identifies a great variability of the untreated disease. Over 7 years nearly half appeared to show no progression, the other half showed progression of their damaged area but this was slow and often did not result in a change of their MD index. There was a small group, who showed rapidly advancing disease, which was likely lead to visual handicap. Moreover, it was then attempted to study risk factors, other than intraocular pressure. Gender, ethnic background, migraine and the presence of disc hemorrhage adversely influence the course of the disease and may therefore account for some of the variability in the course of the disease. normal tension glaucoma, randomized multicenter study.

Visual field and optic disc progression in patients with different types of optic disc damage: a longitudinal prospective study.

OBJECTIVE: To evaluate the incidence of visual field and optic disc progression in glaucoma patients with distinct patterns of optic disc damage. DESIGN: Prospective, observational case series. PARTICIPANTS: One hundred five patients with open-angle glaucoma. METHODS: Baseline optic disc photographs of 105 study eyes of 105 patients were reviewed by 2 masked observers and classified according to patterns of disc damage into the following categories: focal, myopic, senile sclerotic, and generalized disc damage. Patients were followed up every 6 months with standard automated perimetry (SAP), high-pass resolution perimetry (HRP), and scanning laser tomography (SLT) with the Heidelberg Retina Tomograph. MAIN OUTCOME MEASURES: Visual field (SAP and HRP) and optic disc (SLT) progression were determined according to predefined criteria. RESULTS: Twenty-four eyes were classified into the focal, 8 into the myopic, 12 into the senile sclerotic, and 28 into the generalized group. Eyes from 33 patients could not be classified by the observers into any of these groups and were excluded from further analysis. Although intraocular pressure during follow-up was similar among the four groups, some differences in frequency of progression were observed. Patients with senile sclerotic discs had the lowest rates of visual field progression (both with SAP and HRP) and optic disc progression, although the differences were significant only for optic disc progression (P = 0.05). CONCLUSIONS: Patients with senile sclerotic discs showed a tendency towards less visual field and optic disc progression when compared with patients with other types of disc damage.

Factors that predict the benefit of lowering intraocular pressure in normal tension glaucoma.

PURPOSE: To study whether the benefit of lowering of intraocular pressure (IOP) varies according to certain traits. DESIGN: Randomized clinical trial, secondary analysis. METHODS: Visual field data were analyzed from 144 subjects (144 eyes) randomized not to receive IOP-lowering treatment or to have the IOP lowered by 30%. Survival analyses were applied to compare times to progression between groups. Changes in mean deviation global index over time were compared with multilevel random effects models. RESULTS: By univariate analysis, the most readily demonstrated treatment benefit occurred in patients without baseline disk hemorrhage, of female gender, with family history of glaucoma, without family history of stroke, without personal history of cardiovascular disease, and with mild disk excavation; IOP lowering benefited females with migraine (P <.05) but perhaps without eliminating all migraine-associated risk. CONCLUSIONS: It is suggested that different factors may contribute to the glaucomatous optic neuropathy in different cases of normal tension glaucoma, interacting with IOP to different degrees and, thereby, affecting the magnitude of benefit of IOP lowering. Further study is required to establish interactions that would have implications for understanding the disease mechanisms in glaucomatous cupping, for guiding development of new treatment modalities, and for making clinical decisions regarding prognosis and management of individual patients.