Natural History of Open-Angle Glaucoma

Abstract

Objective This article, based on the Early Manifest Glaucoma Trial (EMGT), provides prospective natural history data on progression of glaucomatous field defects in 3 of the most common glaucoma types. Design Cohort of EMGT patients randomized to the untreated control group and followed up to the time of progression, when treatment could be initiated. Participants We evaluated 118 control patients: 46 with high-tension glaucoma (HTG), 57 with normal-tension glaucoma (NTG), and 15 with pseudoexfoliation glaucoma (PEXG). Methods Visual fields were tested every 3 months with the Humphrey 30-2 Full Threshold test program. Main Outcome Measures Linear regression analyses of the perimetric mean deviation (MD) values were performed, and the rate of progression was defined as the regression coefficient in decibels per year. Percentages of progressed eyes and time to progression were determined using EMGT event-based predetermined progression criteria derived from Glaucoma Change Probability Maps. Results The median and interquartile rates of visual function loss were −0.40 (1.05) dB/year overall and −0.46 (1.61) in HTG, −0.22 (0.65) in NTG, and −1.13 (6.13) in PEXG. Thus, interpatient variability was large. Mean rates were considerably higher than medians: −1.08 dB/year overall, −1.31 in HTG, −0.36 in NTG, and −3.13 in PEXG. Differences in median visual function progression rates among groups were statistically significant (NTG vs. HTG, P = 0.003; PEXG vs. non-PEXG, PP = 0.002). By 6 years, 68% of patients had progressed overall, 74% of those with HTG, 56% of those with NTG, and 93% of those with PEXG ( P = 0.012). Median time to progression also differed considerably among groups: 19.5 months in PEXG, 44.8 months in HTG, and particularly 61.1 months in NTG ( P<0.0001). Conclusions In this 6-year follow-up study, the median untreated rate of progression corresponded to advancing from normal visual function to blindness in approximately 70 years, whereas on the basis of the mean rate, visual function would show the same deterioration in approximately 25 years. Large differences existed among patients and different glaucoma types, with PEXG progressing considerably faster than HTG, and NTG progressing at the lowest rate. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.