Reproducibility of Retinal Nerve Fiber Layer and Macular Ganglion Cell Layer Thickness Measurements by Optical Coherence Tomography in Myopic Eyes

Precis: In myopic eyes, reproducibility of circumpapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer thickness measurement by optical coherence tomography (OCT) showed excellent reproducibility except for the temporal quadrant RNFL thickness measurement.

Purpose: The aim of this study was to evaluate the long-term reproducibility of circumpapillary RNFL and macular ganglion cell-inner plexiform layer (GCIPL) thickness measurements using OCT in myopic eyes.

Methods: Sixty-five eyes with moderate-to-high myopia (spherical equivalent <-3.0 D, myopia group) and 53 eyes with low-to-no myopia (spherical equivalent ≥-3.0 D, control group) without ocular disorders, such as glaucoma or retinal diseases, were included. Three serial OCT scans recorded at 1-year intervals were analyzed. Reproducibility was evaluated using within-subject SD (Sw), coefficient of variation (CVw), and intraclass correlation coefficient (ICC).

Results: Mean±SD refractive error was -0.30±0.80 and -6.26±2.45 D for control and myopia groups, respectively. The myopia group had thinner superior, inferior, and nasal quadrant RNFL, thicker temporal quadrant RNFL, and thinner GCIPL than the control group (P<0.05), except for the minimum and superotemporal GCIPL thicknesses (P>0.05). The myopia group had lower reproducibility in temporal quadrant RNFL thickness (Sw, 2.57 μm; CVw 3.27%; ICC, 0.979) than the control group (Sw, 1.80 μm; CVw 2.59%; ICC, 0.989), whereas in other sectors of RNFL and all GCIPL parameters, comparable reproducibility was observed between the 2 groups.

Conclusions: Long-term reproducibility of RNFL and GCIPL thickness measurements in moderate-to-high myopia was comparable to that of low-to-no myopia, except RNFL thickness in the temporal quadrant. These findings should be considered when detecting RNFL and GCIPL changes.