Glaucomas: Managing normal-tension glaucoma

Abstract

Information available in the literature on how to determine the target pressure for a normal-tension glaucoma (NTG) patient is scarce. In the Collaborative Normal-Tension Glaucoma Study (CNTGS) [1, 2], there is no clearly defined single intraocular pressure (IOP) level below which an individual eye is completely safe from developing further glaucomatous damage. In the CNTGS, progression occurred in 35% of untreated eyes (mean IOP 16.0 mmHg) vs. 12% of treated eyes (mean IOP 10.6 mmHg reduced from a mean baseline IOP of 16.9 mmHg). Probability of nonprogression (or survival) in NTG patients determined by the Kaplan Meier life table analysis is shown in Fig. 43.1 [2]. Importantly, the study also demonstrated that many patients with NTG in the untreated randomization arm did not progress. Addi-tionally, a number of enrolled patients showed no progression while in the prerandomization observation phase and were therefore never randomly assigned to either the treatment or nontreatment arms. (The CNTGS enrolled 230 patients but did not randomize them to either arm of the study [observation arm vs. a 30% IOP reduction arm] unless they showed a visual field defect threatening fixation or had had recent glaucomatous progression in the visual field or on the optic nerve.) It was concluded that those patients destined to be nonprogressors or only to progress slowly would derive little benefit, if any, from treatment. Moreover, it should be noted that although progression was less likely in the treated arm a number of patients' glaucoma continued to progress despite the 30% IOP reduction from baseline. © 2010 Springer-Verlag Berlin Heidelberg.