Characteristecs of Visual Field Progression in Normal Tension Glaucoma

Park, Chan Soo; Yoon, Hee Seong; Rho, Sae Heun

Abstract

We performed a retrospective study on the characteristics of visual field progression among 76 eyes of 41 patients who were diagnosed for normal tension glaucoma, using linear regression analysis of global indices(MD, CPSD), mean thresholds of 10 GHT clusters, and thresholds of 52 individual locations. Those patients were identified who had taken seven of more threshold visual field tests over a period of at least 2 years. The results were as follos; 1. There were 18 eyes(23.7%) of 13 patients where MD, CPSD, one or more clusters, of one or more locations was deteriorated. Linear regression of global indices identified 5 subjects(6.6%) with significant decline in MD and 3 subjects(3.9%) with significant progression of CPSD. Twelve sujects(15.8%) had more than one progressive GHT cluster. Fourteen subjects(18.5%) had more than one progressive individual test locations. 2. Deterioration of 2dB or more per year was found in the superior fields more frequently than inferior and there was increasing frequency of visual field progression in superior and inferior fields. The spatial distribution of individual locations that deteriorated was similar to that of clusters. 3. Age, mean IOP, IOP reduction rate and drug used was not related to visual field progression in normal tension glaucoma. These findings suggest that linear regression is a method to detect progression and estimat the magnitude of increase in field loss objectively and has the potential to identify those persons whose trend is sufficiently strong enough to exceed the variability in the data. It is thought that long-term follow-up and appropriate frequency of visual field testing give important information on the clinical characteristics of field progression in glaucoma.