Since OCT images of a rat cochlea were reported,22 many studies evaluating the cochlea using OCT have been conducted. Sepehr et al. visualized porcine cochlea through OCT.8 Instead of decalcification, they thinned the bone from the basal turn of the cochlea, keeping the endosteum intact. Gao et al. quantitatively analyzed the soft tissue of the cochlear using wild-type and Tecta transgenic mice in vitro.23 In addition, the superiority of OCT over conventional histology was indicated by the SD-OCT detection of anatomical changes in the organ of Corti during postnatal cochlear development. In that study, the apical bone in the otic capsule was removed to minimize unwanted scattering. Tona et al. reported that OCT is useful for the evaluation of EH using Slc26A4(−/−) mice in vivo.17 In that study, the second turn was chosen to estimate EH because of the limited penetration depth of OCT. The hearing level was estimated and OCT images and histological findings were compared in Slc26A4(−/−), Slc26A4(+/−), and Slc26A4(+/+) mice. Kakigi et al. visualized the cochlea of a guinea pig using OCT. The feasibility of OCT for quantitative assessment of the endolymphatic space, organ of Corti, and lateral wall was evaluated by comparison with H&E-stained images using a surgically induced EH model,11 a model of deafness induced by kanamycin-ethacrynic acid,24 and a model of strial atrophy induced by streptomycin sulfate perfusion.25 Unlike the procedure utilized in the study by Tona et al.,17 in this study, cochlear OCT images were acquired in vitro after decalcification using EDTA to achieve a high resolution. In the current study, 3-D reconstruction of the OCT images was performed and the hearing status was evaluated at different time points after surgical induction of EH. Hearing loss is one of the essential symptoms of Meniere’s disease. Destructive change by recurrent distension of Reissner’s membrane causes aggravation of hearing status; hence, the extent of EH is related to the hearing level. In this study, the ABR thresholds of the right ear increased at serial measurement postoperatively, which indirectly supports the correlation between pathologic change and hearing change. These procedures were not included in the above-mentioned studies.