Retinal Nerve Fiber Layer Measurement Repeatability in Scanning Laser Polarimetry With Enhanced Corneal Compensation

Abstract

Objective To investigate the measurement repeatability of the various standard retinal nerve fiber layer (RNFL) parameters in scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC, released for investigational use on the commercially available GDx with variable corneal compensation, Carl Zeiss Meditec Inc, Dublin, CA) in healthy eyes, eyes with ocular hypertension (OHT), and glaucomatous eyes. Design Cross-sectional observational study. Participants Sixteen healthy subjects, 32 subjects with OHT, and 35 patients with primary open-angle glaucoma. Methods Eighty-three eyes of eighty-three white participants were imaged with SLP ECC 3 times on a same day. We determined the intraeye RNFL measurement repeatability. Main Outcome Measures Intraeye within-subject standard deviation (Sw), repeatability coefficient, and the 2-way mixed intraclass correlation coefficient for various standard RNFL parameters in SLP ECC. Results The repeatability of the RNFL measurements was generally good. In glaucomatous eyes, the Sw and repeatability coefficient for the nerve fiber indicator and temporal-superior-nasal-inferior-temporal average were statistically significantly higher than in healthy eyes and eyes with OHT. In each group, the intraclass correlation coefficient values were generally similar across the parameters, except for the intereye symmetry. The Sw values for various parameters were generally considerably less than 9% of the measurement spectrum. Conclusions RNFL measurements by SLP ECC had, in general, a good measurement repeatability, although some parameters seemed to be less stable in glaucomatous eyes than in healthy eyes and eyes with OHT. SLP ECC may therefore probably be employed for the detection of glaucomatous progression.