Objective: To test the hypothesis that there was a temporal change in the retinal microstructure after decompression surgery for chiasmal compression, the 1-year longitudinal changes in the inner and outer retinal thickness after decompression surgery were analyzed using spectral-domain optical coherence tomography (SD-OCT) with linear mixed-effects models. Methods: SD-OCT was obtained from 87 eyes with chiasmal compression and compared to 100 healthy controls. The preoperative and 1-year postoperative longitudinal changes in the retinal layer thickness were measured. The thickness of each of the following retinal layers was analyzed: the macular retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), the inner plexiform layer (IPL), the inner nuclear layer, the outer plexiform layer, the outer nuclear layer, and the photoreceptor layer. Results: The RNFL, GCL, and IPL showed thinning at a rate of 1.068 μm/year (95% confidence interval [CI], 0.523, 1.613), 1.189 μm/year (95% CI, 0.452, 1.925), and 1.177 μm/year (95% CI, 0.645, 1.709), respectively, after decompression surgery. The preoperative thickness of the intra-retinal layer was associated with postoperative visual field (VF) recovery (RNFL, odds ratio [OR] = 1.221, 95% CI, 1.058, 1.410; GCL, OR = 1.133, 95% CI, 1.024, 1.254; and IPL, OR = 1.174, 95% CI, 1.002, 1.376). Conclusions: The changes in retinal microstructure persisted and progressed in eyes with chiasmal compression after decompression surgery. The findings provide insight into the biological and anatomical sequelae following chiasmal compression. The preoperative thickness of the inner retinal layers was associated with postoperative VF recovery.