Unprecedented Imaging Resolution of the Retina

Article: Researchers Set New Resolution Record for Imaging the Human Eye
Source: The Optical Society, via ScienceDaily
Article: NIH-led team sets new bar in retinal imaging
Source: National Eye Institute
Published: March 11, 2021

Imaging of the retina is limited by diffraction through apertures such as the pupil, which bends the light and essentially becomes a secondary source of waves. Diffraction limits image resolution. Additionally, the optics of refraction by the cornea and lens, such as transverse and longitudinal aberrations, further decrease image resolution. A team of researchers at the National Eye Institute developed a new adaptive optics technique called non-confocal split-detection to overcome some of these challenges for enhanced imaging of the photoreceptor mosaic of the retina. Interestingly, they did so by reducing the amount of light entering the eye, by strategically blocking the light in the center of a beam to form a hollow ring of light. Though this produced better transverse resolution of the retina, it also reduced axial resolution. The researchers compensated for this by blocking the light coming back from the retina using a sub-Airy disk, a tiny pinhole. The imaging tweak yielded 33% increase in transverse resolution and 13% improvement in axial resolution compared to traditional adaptive optics scanning light ophthalmoscopy. Unlike other methods of imaging that overcome the diffraction barrier by using more light, this technique reduces the amount of light to more safely image living human eyes. When applied to the eyes of five healthy volunteers (after theoretical simulations), the imaging technique could visualize "a circularly shaped subcellular structure in the center of cone photoreceptors that could not be clearly visualized previously." The enhanced resolution is particularly useful for imaging the cones tightly packed at the fovea as well as imaging the more numerous, but smaller, rods elsewhere. The researchers hope that this first step toward routine sub-diffraction imaging of subtleties and changes in size, shape, and distribution of photoreceptors will aid in early detection and intervention of retinal diseases.

My rating of this study: ⭐⭐⭐⭐⭐

Further reading: Do you 'need' or just 'want' that new diagnostic imaging device?