Purpose: To describe an event analysis (EA) for monitoring Heidelberg Retina Tomograph (HRT) progression and to establish specificity, detection rate, and agreement with visual field progression by application to longitudinal data.
Design: Retrospective analysis of data from a randomized controlled trial.
Participants: One hundred ninety-eight ocular hypertensive and 21 control subjects.
Methods: Change criteria were derived from rim area (RA) repeatability coefficients for different levels of image quality. Event analysis 1 (EA1) through EA4 were applied to longitudinal series of HRT images acquired from the ocular hypertensive and the control cohorts: EA1 (change confirmed in 2 of 3 consecutive tests in 1 or more sector), EA2 (2 of 3 in 2 or more sectors), EA3 (3 of 3 in 1 or more sector), EA4 (3 of 3 in 2 or more sectors). Specificity (1 minus false positive results) was estimated by the proportions of progressing controls and significantly improving subjects. Progression rates were compared with Advanced Glaucoma Intervention Study (AGIS) visual field (VF) criteria, an HRT trend analysis, and a VF trend analysis, with specificity matched at 95%.
Main outcome measures: Estimated specificity, progression rate, and agreement between progression techniques.
Results: Specificity estimates were 76.2% to 88.1% (EA1), 94.1% to 95.2% (EA2), 92.2% to 95.2% (EA3), and 99.1% to 100% (EA4). Of ocular hypertensive (OHT) subjects, 45.4%, 28.3%, 26.3%, and 16.2% were identified as progressing by each strategy, respectively. With specificity at 95%, 12.1% of OHT subjects progressed by both EA2 and AGIS criteria, with a median time to progression of 3.2 and 3.6 years, respectively. By EA2 alone, 16.2% progressed, and 9.6% progressed by AGIS criteria alone. The RA trend analysis identified 12% of OHT subjects as progressing.
Conclusions: The HRT EA represents a simple technique, taking into account image quality. In this cohort, it had a higher detection rate of progression, at 95% specificity, than RA trend analysis and the VF progression criteria.