Comparison of Widefield and Circumpapillary Circle Scans for Detecting Glaucomatous Neuroretinal Thinning on Optical Coherence Tomography

PURPOSE: Our purpose was to compare the effectiveness of detecting progressive retinal nerve fiber layer (RNFL) thickness changes using widefield scans compared to circumpapillary circle scans derived from optic disc volume scans when using a manual region-of-interest (ROI) approach. METHODS: In a prospective observational study, a total of 125 eyes diagnosed clinically with glaucoma or suspected glaucoma that had both widefield (12 × 9 mm) and optic disc (6 × 6 mm) scans obtained at least one year apart were included. Changes in the RNFL thickness between the two visits were evaluated within region(s) of observed or suspected glaucomatous damage, which were manually outlined after reviewing key features from each scan on the second visit (described as a manual ROI approach). Within ROI(s), changes in the widefield and circumpapillary RNFL thickness (wfRNFL(ROI) and cpRNFL(ROI)), as well as in the global circumpapillary RNFL thickness (cpRNFL(G)), were determined. The performance of these three methods for detecting progressive changes was compared using longitudinal signal-to-noise ratios (SNRs), whereby the rate of change determined by each method was normalized by individualized estimates of measurement variability and age-related change. RESULTS: On average, the longitudinal SNRs for the wfRNFL(ROI), cpRNFL(ROI), and cpRNFL(G) methods were −0.57, −0.38, and −0.23 y(−1), respectively, being significantly more negative for the wfRNFL(ROI) than the latter two methods (P ≤ 0.009). CONCLUSIONS: Progressive RNFL thickness changes were more effectively detected on widefield optical coherence tomography (OCT) scans using a manual ROI approach compared to conventional derived circumpapillary circle scans. TRANSLATIONAL RELEVANCE: Widefield OCT scans show promise for improving the detection of glaucomatous progression.