Reproducibility of peripapillary retinal nerve fibre layer thickness measurements with spectral domain optical coherence tomography in normal and glaucomatous eyes

Aim To determine reproducibility of peripapillary retinal nerve fibre layer thickness (RNFLT) measurements by spectral optical coherence tomography scanning laser ophthalmoscope (Spectral OCT/SLO) in normal and glaucomatous eyes. Methods 61 normal subjects and 41 glaucoma patients underwent three RNFLT measurement by Spectral OCT/SLO in one of the eyes with a rest of 1 h between each scan. The series was repeated on three different days within 1-month period. Intrasession, intersession reproducibility of average, quadrant and clock hour RNFLT measurements were calculated for both groups. All scans were acquired by a single operator after dilation. Results The intrasession intraclass coefficient correlations for mean RNFLT in normal and glaucomatous eyes were 0.994 and 0.998, respectively. The intrasession test coefficient of variation (CV) ranged from 1.2% for mean RNFLT to 5.1% for temporal clock hour in normal eyes and 1.3% for mean RNFLT to 3.6% for nasal quadrant in glaucomatous eyes. The intersession intraclass coefficient correlation for mean RNFLT in normal and glaucomatous eyes was 0.988. Intersession CV ranged from 3.96% for mean RNFLT to 9.56% for temporal clock hour in normal eyes and 3.28% for mean RNFLT to 13.39% for temporal clock hour in glaucoma patients. Conclusion The RNFLT measurement showed increased variability for narrower peripapillary areas, nasal and temporal quadrants showed higher variability than superior and inferior quadrants in normal and glaucomatous eyes. Spectral OCT/SLO demonstrated excellent intrasession and intersession reproducible measurements of peripapillary RNFLT in both groups. This finding may be useful for diagnosis and monitoring the progression of glaucoma and other optic neuropathies with spectral OCT/SLO.