Predictors of Atypical Birefringence Pattern in Scanning Laser Polarimetry

Abstract

Purpose: : To evaluate predictors of atypical birefringence patterns (ABP) observed in scanning laser polarimetry.

Methods: : A total of 179 eyes from 82 normal subjects and 97 glaucoma patients were included. The retinal nerve fiber layer in each eye was imaged sequentially with GDx VCC and GDx ECC (Carl Zeiss Meditec, Dublin, CA). The associations between the typical scan score (TSS) and age, axial length, refractive error, parapapillary atrophy (PPA), and visual field MD were evaluated with univariate and multivariate regression analyses.

Results: : 23.5%(42/179) and 5.0%(9/179) of subjects had ABP(TSS<80) with GDx VCC and GDx ECC, respectively. For both GDx VCC and ECC, the TSS was significantly correlated with age, axial length, refraction, and PPA, but not with visual field MD. After adjusting the effect of covariates, the axial length and PPA were significantly associated with GDx VCC TSS, whereas the axial length was the only predictor for GDx ECC TSS. Myopic eyes were more likely to develop ABP in both GDx VCC and ECC.

Conclusions: : Axial length is a significant predictor for ABP with both GDx VCC and GDx ECC. Caution should be exercised in interpreting the results of scanning laser polarimetry in eyes with long axial length or myopia.

Keywords: imaging/image analysis: clinical