Diffractive corneal inlay for presbyopia

A conceptually new type of corneal inlays for a customized treatment of presbyopia is presented. The diffractive inlay consists on a small aperture disc having an array of micro‐holes distributed inside the open zones of a Fresnel zone plate. In this way, the central hole of the disc lets pass the zero order diffraction and produces an extension of the depth of far focus of the eye, while the diffracted light through the holes in the periphery produce the near focus. Additionally, the micro‐holes in the inlay surface fulfill the essential requirement of allowing the flow of nutrients through it to the cells of the corneal stroma. Theoretical and optical‐bench experimental results for the polychromatic axial Point Spread Function (PSF) were obtained, showing an improved performance compared to the small aperture corneal inlay currently in the market (Kamra). Images of a test object, obtained at several vergences in the surroundings of the far and near foci, are also shown. Picture: Simulation of the appearance of the Diffractive corneal inlay on a real eye. A new concept of corneal inlay, for the treatment of presbyopia, is proposed. In it, the micro‐holes on the inlay surface, that are essential to allow the flow of nutrients, are arranged to take advantage of the unwanted diffracted light in previous small aperture inlays, for creating a true near focus. The inlay design can be customized. Experimental results demonstrate the high performance of this proposal in comparison with current designs.