PURPOSE:To analyze the repeatability of thickness measurements of the central macula, ganglion cell-inner plexiform layer (GC-IPL), and retinal nerve fiber layer (RNFL) using spectral-domain optical coherence tomography (SD-OCT) before and after treatment of macular edema in branch retinal vein occlusion (BRVO). METHODS:We analyzed patients with BRVO who visited our retinal clinic. The repeatability of the thickness measurements were compared using the intraclass correlation coefficient (ICC) and coefficient of variation (COV) of affected versus normal fellow eyes. RESULTS:The average thicknesses of the central macula, RNFL, and GC-IPL were 371.28 μm, 105.60 μm, and 61.88 μm, respectively, in affected eyes with macular edema before treatment, and the ICCs were 0.978, 0.919, and 0.705, respectively. The average thicknesses were 244.98 μm, 96.70 μm, and 82.70 μm, respectively, in affected eyes without macular edema after treatment, and the ICCs were 0.999, 0.975, and 0.928, respectively. After resolution of macular edema, the average thickness of the GC-IPL increased, whereas that of the central macula and RNFL significantly decreased (P < 0.05); all of the ICCs increased compared to pretreatment values. In normal fellow eyes, the average thicknesses were 250.98 μm, 93.50 μm, and 83.84 μm, respectively, and the ICCs were 0.996, 0.995, and 0.994, respectively. CONCLUSIONS:After treatment of macular edema, the repeatability and thickness of the GC-IPL increased, along with reduction in the central macular thickness. This resulted from auto-segmentation errors following macular contour changes and unstable gazes of the patients due to decreased visual acuities in BRVO with macular edema.