Transscleral optical phase imaging of the human retina

In vivo observation of the human retina at the cellular level is crucial to detect the first signs of retinal diseases and properly treat them. Despite the phenomenal advances in adaptive optics systems, clinical imaging of many retinal cells is still elusive due to the low signal-to-noise ratio induced by transpupillary illumination. We present a transscleral optical phase imaging method, which relies on high-angle oblique illumination of the retina, combined with adaptive optics, to enhance cell contrast. Examination of 11 healthy volunteer eyes, without pupil dilation, shows the ability of this method to produce in vivo images of retinal cells, from the retinal pigment epithelium to the nerve fibre layer. This method also allows the generation of high-resolution label-free ex vivo phase images of flat-mounted retinas. The in vivo images with 4.4 degrees x 4.4 degrees field of view are recorded in less than 10 s, opening new avenues in the exploration of healthy and diseased retinas. Transscleral optical phase imaging, which is based on transscleral flood illumination of the retina, is demonstrated to provide cellular-resolution, label-free, high-contrast images of the retinal layers over a large field of view without the drawback of a long exposure time.