Reproducibility of peripapillary retinal nerve fiber layer thickness measurements using spectral domain OCT in Brazilian patients

Abstract

Purpose: To evaluate the reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness measurements in normal eyes and eyes with glaucoma using spectral domainoptical coherence tomography (SDOCT). Methods: One eye of 79 normal and 72 glaucoma patients was analyzed. All patients underwent a complete ophthalmological examination, including visual acuity testing; intraocular pressure, slit-lamp examination, indirect ophthalmoscopy; and the glaucoma group underwent achromatic perimetry with the 24-2 SITA Fast Humphrey Field Analyzer. All patients' eyes were scanned using the spectral domain optical coherence tomography - Spectralis® and one of them was chosen randomly. Three consecutive circular B-scan centered at the optic disc were performed in one visit. Results: The intraclass correlation coefficient (ICC), coefficient of variation and test-retest variabilityfor the mean retinal nerve fiber layer thickness were respectively: 0.94, 2.56% and 4.85 μm for the normal group and 0.93, 4.65% and 6.61 μm for the glaucomatous group. The intraclass correlation coefficient for retinal nerve fiber layer thickness in all quadrants were all excellent in both groups, with the superior quadrant having the highest ICCs (0.964) in glaucomatous eyes and nasal quadrant measurements having the lowest (0.800), but still excellent in eyes without glaucoma. The coefficient of variation was between 2.56% - 8.74% and between 4.65% - 11.44% in normal and glaucomatous group respectively. The test-retest variability was between 4.85 μm and 11.51 μm in the normal group and between 6.61 μm and 14.24 μm in the glaucomatous group. The measurements in glaucomatous eyes were more variable than normal eyes. Conclusions: Spectral domain optical coherence tomography showed excellent reproducibility with regard to retinal nerve fiber layer thickness measurements in normal and glaucomatous eyes.