Super-resolution retinal imaging using optically reassigned scanning laser ophthalmoscopy

Super-resolution optical microscopy techniques have enabled the discovery and visualization of numerous phenomena in physics, chemistry and biology1–3. However, the highest resolution super-resolution techniques depend on nonlinear fluorescence phenomena and are thus inaccessible to the myriad applications that require reflective imaging4,5. One promising super-resolution technique is optical reassignment6, which so far has only shown potential for fluorescence imaging at low speeds. Here, we present novel advances in optical reassignment to adapt it for any scanning microscopy, including reflective imaging, and enable an order of magnitude faster image acquisition than previous optical reassignment techniques. We utilized these advances to implement optically reassigned scanning laser ophthalmoscopy, an in vivo super-resolution human retinal imaging device not reliant on confocal gating. Using this instrument, we achieved high-resolution imaging of living human retinal cone photoreceptor cells (determined by minimum foveal eccentricity) without adaptive optics or chemical dilation of the eye7. The implementation of optically reassigned scanning laser ophthalmoscopy enables in vivo photon reassignment super-resolution imaging and high-resolution imaging of living human retinal cone photoreceptor cells without adaptive optics or chemical dilation of the eye.