Abstract
Abstract: :
Purpose: To compare the retinal nerve fiber layer (RNFL) thickness obtained by scanning laser polarimetry with variable cornea compensator (GDx–VCC) and optical coherence tomography (Stratus OCT) in glaucomatous patients. Methods: Twenty–nine eyes of eighteen patients were included. The patients had glaucoma, best–corrected visual acuity of 20/60 or better, neither significant media opacity nor other significant ocular disease. Peripapillary RNFL thickness was obtained by GDx and OCT using circles with radius of 1.4 mm, 1.8 mm and 2.2 mm centered on the optic disc. The average RNFL thickness of each circle obtained by both devices was compared. A linear mixed model was used to adjust for correlations between measurements of both eyes of the same individual. Results:The Lin’s concordance correlation coefficients between OCT and GDx measurements at 1.4–mm, 1.8–mm and 2.2–mm radii circles were 0.07 (P=0.03), 0.06 (P=0.13) and 0.11 (P=0.09), respectively. The mean differences between OCT and GDx measurements at 1.4–mm, 1.8–mm and 2.2–mm radii circles were 42.35 µm (95% Confidence Interval [CI]: 37.46 to 47.25 µm; P<0.001), 31.00 µm (95% CI: 26.37 to 35.63 µm; P<0.001) and 24.50 µm (95%CI: 19.99 to 29.00 µm; P<0.001), respectively. The mean ratios of OCT to GDX measurements at 1.4–mm, 1.8–mm and 2.2–mm radii circles were 2.1 (95% CI: 1.92 to 2.20; P<0.001), 1.9 (95% CI: 1.7 to 2.1; P<0.001) and 1.8 (95% CI: 1.6 to 1.9; P<0.001), respectively. Conclusions: There is poor agreement between OCT and GDx RNFL thickness measurements in glaucomatous patients. The RNFL thickness obtained using Stratus OCT is about two–fold thicker than GDx–VCC measurements.
Keywords: nerve fiber layer • clinical (human) or epidemiologic studies: systems/equipment/techniques • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)