Thickness of the Macula, Retinal Nerve Fiber Layer, and Ganglion Cell Layer in the Epiretinal Membrane: The Repeatability Study of Optical Coherence Tomography

PURPOSE. To analyze the repeatability of measurements of the thicknesses of the macula, retinal nerve fiber layer (RNFL), and ganglion cell inner plexiform layer (GCIPL) using spectral-domain optical coherence tomography (SD-OCT) in the epiretinal membrane (ERM). METHODS. The prospective study analyzed patients who visited our retinal clinic from June 2013 to January 2014. An experienced examiner measured the thicknesses twice using macular cube 512 x 128 and optic disc cube 200 3 200 scans. The repeatability of the thicknesses of the macula, RNFL, and GCIPL were compared using the intraclass correlation coefficient (ICC) of two groups based on the central macular thickness (group A, <= 450 mu m; group B, > 450 mu m). RESULTS. A total of 88 patients were analyzed. The average thicknesses of the central macula, RNFL, and GCIPL were 256.5, 96.6, and 84.4 mu m, respectively, in the normal fellow eye and 412.3, 94.6, and 56.7 mu m in the affected eye. The ICCs of the central macula, RNFL, and GCIPL were 0.995, 0.994, and 0.996, respectively, for the normal fellow eye and 0.991, 0.973, and 0.881 for the affected eye. The average thicknesses of the central macula, RNFL, and GCIPL in group A were 360.9, 93.5, and 63.4 mu m, respectively, and the ICCs were 0.997, 0.987, and 0.995. The thicknesses in group B were 489.5, 96.2, and 46.6 mu m, respectively, and the ICCs were 0.910, 0.942, and 0.603, significantly lower repeatability compared with group A (P < 0.05). CONCLUSIONS. The macular contour change with the ERM results in low repeatability and tendency to be measured thinner in GCIPL thickness using SD-OCT. This can be explained by the unstable gaze of the patient due to decreased visual acuity and autosegmentation error following changes in the macula.