Overcoming the resolution limit in retinal imaging using the scattering properties of the sclera

In-vivo imaging of the eye's fundus is widely used to study eye's health. State of the art Adaptive Optics devices can resolve features up to a lateral resolution of 1.5 um. This resolution is still above what is needed to observe subcellular structures such as cone cells (1-1.25 um diameter). This limit in resolution is due to the small numerical aperture of the eye when the pupil is fully dilated (max 0.24). In our work, we overcome this limit using a non-standard illumination scheme. A laser beam is shined on the lateral choroid layer, whose scattered light is illuminating the eye's fundus. Thanks to a Spatial Light Modulator the scattered light from the choroid layer can be manipulated to produce a scanning focus spot on the fundus. The intensity of the reflected light from the fundus is collected from the pupil and used for reconstructing the image.