AIM: To evaluate the diagnostic ability of macular ganglion cell-inner plexiform layer (GCIPL) thickness obtained by spectral-domain optical coherence tomography (SD-OCT) in discriminating non-highly myopic eyes with preperimetric glaucoma (PPG) from highly myopic healthy eyes. METHODS: A total of 254 eyes, including 76 normal controls (NC), 116 eyes with high myopia (HM) and 62 non-highly myopic eyes with PPG were enrolled. The diagnostic ability of OCT parameters was accessed by the areas under the receiver operating characteristic (AUROC) curve in two distinguishing groups: PPG eyes with non-glaucomatous eyes including NC and HM (Group 1), and PPG eyes with HM eyes (Group 2). Differences in diagnostic performance between GCIPL and RNFL parameters were evaluated. RESULTS: The minimum (AUROC curve of 0.782), inferotemporal (0.758) and inferior (0.705) GCIPL thickness were the top three GCIPL parameters in discriminating PPG from non-glaucomatous eyes, all of which had statistically significant lower diagnostic ability than average RNFL thickness (0.847). In discriminating PPG from HM, the best GCIPL parameter was minimum (0.689), statistically significant lower in diagnostic ability than average RNFL thickness (0.789) and three other RNFL thickness parameters of temporal and inferotemporal clock-hour sectors. CONCLUSION: The minimum GCIPL thickness is the best GCIPL parameter to detect non-highly myopic PPG from highly myopic eyes, whose diagnostic ability is inferior to that of average RNFL thickness and RNFL thickness of several temporal and inferotemporal clock-hour sectors. The average RNFL thickness is recommended for discriminating PPG from highly myopic healthy eyes in current clinical practice in a Chinese population.