A Physicist's View of the Eye

Abstract

Melanie will discuss how she has and collaborators have applied physics techniques to advance the understanding of the optics of the eye, and to develop novel diagnostic and therapeutic approaches for eye diseases. Her work includes the application of inverse methods used to characterise optical fibres, waveguide theory applied to cone photoreceptors, sinusoidal analysis of circadian rhythms in the eye, adaptive optics, confocal and polarisation imaging used to improve images of the rear of the eye, characterisation of deposits by atomic force microscopy and drug excitation by two photons as a therapy for eye disease. Using an Abel integral inversion technique applied in optical fibres, Campbell measured for the first time, the gradient refractive index variation in the crystalline lens of the eye. She and her collaborators demonstrated that this distribution can be modified by visual experience. Campbell and her collaborators have also shown that the optical quality of the lens varies with age and that the progressive loss of near vision is lens based. These findings inspired a new design for an IOL lens which replaces the living lens during cataract surgery. In another example, adaptive optics, originally developed for astronomy, offers a powerful tool for localizing light within the eye. In turn, this has resulted in the correction of the optical imperfections of the eye, giving images of structures at the rear of the eye with improved resolution and contrast. In addition, adaptive optics can precisely localize light stimuli for therapeutic purposes within the eye. The precise localization of light energy in other at the retina is limited by the optics of the eye. Adaptive optics may enable precise light based therapies in the crystalline lens and retina of the eye.