Intraocular Camera for Retinal Prostheses

Abstract

Abstract: : Purpose: To design a novel miniaturized intraocular video camera for use in conjunction with an epiretinal microelectrode array. Methods: An analysis of possible surgical placements and associated camera design constraints was performed. The optical system utilizes the existing corneal lens and aqueous humor in conjunction with an aspherical lens to allow for sufficient field flattening at the detector plane, thus providing imaging characteristics that are matched to the degree of pixellation required by current and envisioned epiretinal microelectrode arrays. Visual psychophysics techniques were employed to reveal optimal pixellation and image pre– and post–processing requirements, yielding relaxed camera design constraints. Image acquisition in the first prototypes is provided by commercially–available CCD or CMOS [active pixel sensor (APS) array] imaging chips, with provision for custom ASIC imaging chips that are self–contained and include post–image–acquisition processing functions. The entire imaging device is small enough for surgical placement within the crystalline lens sac following a phacoemulsification procedure similar to that commonly used for cataract surgery. Comprehensive optical performance modeling of the implanted device system has been performed to optimize the system design. Results: A second–generation prototype intraocular camera (7 mm x 4 mm) was constructed and tested, demonstrating wide depth and flatness of field. The prototype was sealed and surgically implanted in a canine eye for acute testing. Comparison between pre– and post–surgical images successfully demonstrated the design concept. Conclusions: The replacement of an extraocular (head–mounted) camera with an intraocular camera for retinal prostheses is feasible, providing natural image acquisition using eye movement.

Keywords: retina • optical properties