Comparison of the Rate of Glaucoma Progression by Stage Using Structural and Functional Testing

Abstract

Purpose: : To compare proportion of eyes progressing by various structural and functional parameters in various stages of disease.

Methods: : Charts of 201 patients with the diagnosis of glaucoma or glaucoma suspect followed at 5 glaucoma practices for at least 3 years with a minimum of 5 HVF (24-2 or 30-2) tests and 3 HRT II examinations were reviewed. For each patient, the eye with the higher Glaucoma Staging System (GSS) score was used in the analysis. HVF progression was assessed by Glaucoma Progression Analysis (GPA) and linear regression analysis of mean deviation (MD). HRT-II progression was assessed by Moorfields Regression Analysis (MRA) and at least a 10% change in 3 or more of 5 major stereometric analysis (SMA) parameters. Disease progression according to physician’s clinical impression was recorded. For binary parameters a goodness of fit Chi² test was used to compare the number of patients who progressed in stage 0, stage 1-2, and stage 3-4. MD change per year was compared using ANOVA.

Results: : Mean age of patients was 69±14 yrs. 70 patients had stage 0 disease, 69 had stage 1-2 disease, and 62 had stage 3-4 disease. Mean follow-up was 6.1±2.3 yrs (range 3.0 to 14.7 yrs). The proportion of eyes showing progression by GPA, SMA and MRA was the same in the 3 groups (p>0.05). However, the proportion of eyes showing progression by clinical impression was significantly lower in eyes with stage 0 disease (p=0.02). Average yearly MD change in all eyes (n=201) was -0.32 ± 0.83 dB/yr with progressively higher rates in patients with late stages of glaucoma (-0.04 ± 0.37 dB/yr in stage 0, -0.42 ± 0.58 dB/yr in stage 1-2, and -0.53 ± 1.26 dB/yr in stage 3-4, p=0.001). Assuming that a change in MD of more than 1DB/yr is pathologic, the proportion of eyes progressing was lower among stage 0 eyes (p=0.0004).

Conclusions: : Patients with advanced disease were more likely to deteriorate than those with early disease according to one of the measures of function analyzed, MD, and according to physician’s clinical impression. Structural analysis and GPA did not show differences in the rates of progression by stage of glaucoma.

Keywords: visual fields • optic nerve • perimetry