Objective To interpret the nature of the reflections in outer limiting membrane (OLM), IS/OS and the retinal pigment epithelium (RPE) layer on the three-dimensional optical coherence tomography (3D-OCT). Methods Knowledge of ocular embryology and histology combined with 3D-OCT image feature of clinically relevant cases to interpret the outer retina and RPE layer.Results The highly inner reflective band of RPE layer is composed of the microvilli processes at apex of RPE, melanin granules and possibly tight junctions (zonula occludens), as well as the apical portions of outer segment which is embedded in the villous processes of RPE cells. The highly outer reflective band of RPE layer comprises the numerous highly convoluted basal enfolding of the cell membrane at the basilar surface of RPE cells and Bruch's membrane (BM). While the middle of RPE layer with a higher reflectance may be mainly composed of RPE cell nuclei. Conclusion Ultra structure of retina and information of pathology & physiology for interpretation of the images of OCT has the vital significance.