Comparison of scanning laser polarimetry using variable corneal compensation and retinal nerve fiber layer photography for detection of glaucoma

Abstract

Objective: To compare retinal nerve fiber layer (RNFL) measurements obtained with scanning laser polarimetry (SLP) using variable corneal polarization compensation with standard red-free photography for detection of RNFL damage in glaucoma.

Methods: This observational, cross-sectional study included 1 eye of each of 42 patients with open-angle glaucoma, 32 patients suspected of having glaucoma, and 40 healthy subjects. The RNFL measurements using SLP with variable corneal compensation were obtained within 3 months of red-free photographs. Two independent observers graded RNFL photographs using a standardized protocol. Superior and inferior hemiretinas were scored separately, and a global score was obtained by averaging scores from each hemiretina.

Main outcome measures: The RNFL photography scores were compared with RNFL thickness measurements obtained with SLP. The receiver operating characteristic (ROC) curves were constructed to assess the abilities of the different methods to differentiate glaucoma patients from healthy subjects.

Results: The RNFL thickness decreased with increased RNFL damage as assessed by photographs in both hemiretinas (R(2) = 15%-47%). The area under the ROC curve for the best SLP parameter, Nerve Fiber Indicator, was significantly greater than the area under the ROC curve for the global RNFL photography score (0.91 vs 0.84, P =.03).

Conclusions: A moderate correlation was found between RNFL thickness measurements obtained with SLP and RNFL scores from red-free photographs. Compared with semiquantitative RNFL photography scores, the best SLP parameter had a higher diagnostic accuracy to separate glaucoma patients from healthy subjects.