Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography

The purpose is to study the ability of an event-based analysis of retinal nerve fibre layer (RNFL) attenuation measured by Stratus^® optical coherence tomography (OCT) and to detect progression across the spectrum of glaucoma. Adult glaucoma suspects, ocular hypertensives and glaucoma patients who had undergone baseline RNFL thickness measurement on Stratus OCT and reliable automated visual field examination by Humphrey’s visual field analyser prior to March 2007 and had 5-year follow-up data were recruited. Progression on OCT was defined by two criteria: decrease in average RNFL thickness from baseline by at least 10 and 20 µ. Visual field progression was defined by the modified Hodapp–Parrish–Anderson criteria. Absolute and percentage change in RNFL thickness from baseline was compared in progressors and non-progressors on visual fields. Concordance between structural and functional progression was analysed. 318 eyes of 162 patients were analysed. 35 eyes (11 %) progressed by visual fields, 8 (2.5 %) progressed using the 20 µ loss criterion, while 30 eyes (9.4 %) progressed using the 10 µ loss criterion. In glaucoma suspects, mean absolute RNFL attenuation was 8.6 µ (12.1 % of baseline) in those who progressed to glaucoma by visual fields. OCT was more useful to detect progression in early glaucoma, but performed poorly in advanced glaucoma. The 10 µ criterion appears to be closer to visual field progression. However, the ability to detect progression varies considerably between functional and structural tools depending upon the severity of the disease.