Reproducibility and repeatability of retinal nerve fiber layer parameters measured by scanning laser polarimetry with enhanced corneal compensation in glaucomatous eyes

Abstract

Purpose To determine the reproducibility and repeatability of retinal nerve fiber layer parameters measured using scanning laser polarimetry (SLP) with enhanced corneal compensation (GDx‐ECC) in glaucoma patients. Methods Fifty‐four consecutive glaucomatous subjects were prospectively selected. All participants underwent a comprehensive eye exam and at least a reliable standard automated perimetry (Humphrey, 24‐2 SITA Standard). Only one eye per patient was randomly included in the statistical analysis. Three scans were acquired during the same visit using the GDxPRO (Carl Zeiss Meditec, Dublin, CA). Two additional scans were obtained within a 2‐month period. Intraclass correlation coefficient (ICC), coefficient of variation (COV), and test‐retest variability were calculated for all SLP parameters. Results Mean age was 58.27 ± 8.9 years (p=0.09) and mean deviation of standard automated perimetry was ‐7.04 ± 7.0 dB. ICCs were higher than 0.91 for all SLP parameters. The nerve fiber indicator (NFI) showed the highest ICC in the intra‐test sequence (0.982; 95% confidence interval: 0.972‐0.989; p<0.001). The TSNIT average showed the lowest COVs (4.40% and 4.71% in the intra‐ and inter‐test, respectively). Test‐retest variability for the NFI ranged from 10.6 to 12.8. Conclusion The GDx‐ECC had an excellent intravisit and intervisit reproducibility in glaucoma patients. SLP is an imaging technology that may be useful in monitoring glaucoma progression. Commercial interest