Scanning Protocol Choice Affects Optical Coherence Tomography (OCT-3) Measurements

Abstract

Abstract: : Purpose: To compare retinal nerve fiber layer (RNFL) measurements obtained with different scanning protocols. Methods:Normal subjects, ocular hypertensive and open-angle glaucoma patients were enrolled. The "fast" RNFL scan protocol consists of 3 consecutive circular scans, each containing 256 A-scans taken automatically in one session of 1.92 seconds. The "regular" RNFL scan protocol contains 3 separate circular scans, each of which consists of 512 A-scans and is obtained in 1.28 seconds (total 4.48 seconds). Mean RNFL thickness measurements and mean coefficients of variation (CV) were calculated for each of the scan types. Results:Thirty-one eyes with visual field (VF) defects (31 glaucoma eyes) and 30 eyes with normal VFs (10 normal, and 20 ocular hypertensive eyes) were enrolled. There was no difference in RNFL thickness between fast and regular RNFL scans in the eyes with VF defects (p=0.49, paired t-test), however mean CV was higher in fast than regular RNFL scans (p=0.008). Eyes with normal VFs showed no difference in CV between fast and regular RNFL scans (p=0.87). However there was a trend towards a thicker RNFL measurement using the fast RNFL scan (p=0.06) (Table). Conclusions:Protocol choice affects RNFL thickness measurements and measurement reproducibility.  

Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • clinical (human) or epidemiologic studies: sys