Clinically useful wide‐field high‐resolution retinal imaging optics with a dual‐conjugate adaptive instrument

Abstract

Abstract Purpose The aim of this project is to apply the technique of multi‐conjugate adaptive optics (MCAO) for high‐resolution imaging of the retina over a wide field‐of‐view (FOV). Methods MCAO is the principal technique to overcome the limitations of conventional AO systems by increasing the corrected FOV. The current system incorporates two deformable mirrors (DMs). Optically, these two DMs correspond to separate planes along the optical axis of the eye. This allows the correction of field‐dependent aberrations and subsequent wide‐field high‐resolution retinal imaging over a wide FOV. Normative data from healthy subjects was collected in order to determine clinical potential and limitations. Results We have demonstrated the MCAO concept with a current FOV of 7x7 deg on both model and human eyes. The diffraction‐limited resolution is around 2 µm on the retina, allowing most cone photoreceptors to be resolved. Retinal morphology of healthy subjects was investigated. The estimated cone separation at a retinal eccentricity of 1.2 deg and 2.5 deg from the fovea was 6 µm and 9 µm, respectively, in agreement with the literature. The relatively narrow depth of focus enables us to image different layers of the retina. Focusing on deeper layers allows us to image the cone photoreceptor layer. By focusing on the upper layers we can also image the retinal capillary layer and nerve fibre layer with the same high resolution. Conclusion Our instrument allows retinal features down to 2 µm to be resolved over a 7x7 deg FOV. We believe that this new technique has a future potential for clinical imaging with an impact particularly important for early diagnosis of retinal diseases.