We developed a hybrid deep learning model (HDLM) algorithm that quantitatively predicts macular ganglion cell-inner plexiform layer (mGCIPL) thickness from red-free retinal nerve fiber layer photographs (RNFLPs). A total of 789 pairs of RNFLPs and spectral domain-optical coherence tomography (SD-OCT) scans for 431 eyes of 259 participants (183 eyes of 114 healthy controls, 68 eyes of 46 glaucoma suspects, and 180 eyes of 99 glaucoma patients) were enrolled. An HDLM was built by combining a pre-trained deep learning network and support vector machine. The correlation coefficient and mean absolute error (MAE) between the predicted and measured mGCIPL thicknesses were calculated. The measured (OCT-based) and predicted (HDLM-based) average mGCIPL thicknesses were 73.96 ± 8.81 µm and 73.92 ± 7.36 µm, respectively (P = 0.844). The predicted mGCIPL thickness showed a strong correlation and good agreement with the measured mGCIPL thickness (Correlation coefficient r = 0.739; P < 0.001; MAE = 4.76 µm). Even when the peripapillary area (diameter: 1.5 disc diameters) was masked, the correlation (r = 0.713; P < 0.001) and agreement (MAE = 4.87 µm) were not changed significantly (P = 0.378 and 0.724, respectively). The trained HDLM algorithm showed a great capability for mGCIPL thickness prediction from RNFLPs. Glaucoma is the leading cause of visual impairment worldwide, affecting more than 70 million people 1. Effective screening strategies are important, as most patients do not present any symptoms before the disease has reached the advanced stage 2,3. There has been remarkable progress in glaucoma screening thanks to the development of deep learning algorithms such as convolutional neural networks (CNNs) for visual recognition 4-6. A number of studies have reported the diagnostic performance of the deep learning model as excellent in terms of area under receiver operating characteristic curve (AUC). Ting et al. reported on a deep learning system for multiethnic diabetic cohorts that achieved an AUC of 0.942 7. Li et al. reported a deep learning model that had been trained on a very large-scale dataset with over 48,000 fundus photographs and that achieved an AUC of 0.986 for referable glaucomatous optic neuropathy 6. However, the deep learning models of most of the previous studies require ground truth labeling by human graders. This labeling process is labor-intensive as well as subjective. Spectral domain-optical coherence tomography (SD-OCT) is widely utilized for detection and quantitative assessment of glaucomatous structural loss of retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) 8-11. It is useful not only for diagnosing glaucoma but also for monitoring glaucoma progression even before apparent visual field (VF) change 12,13. Recently, several studies have shown that RNFL thickness and minimum rim width relative to Bruch's membrane opening (BMO-MRW) under SD-OCT can be successfully quantified from monoscopic optic disc