Ehsan Vaghefi
University of Auckland, New Zealand
Title: Physiological optics, a laser ray-tracing system to measure the 3d refractive indices of in-vitro lenses
Biography
Biography: Ehsan Vaghefi
Abstract
Age-related changes to the optical properties of the ocular lens are the leading causes of presbyopia and cataract. We know little about how the optical properties of the lens are established and maintained at the molecular and cellular levels during the natural aging process. The ocular lens has an inherent Gradient of Refractive Index (GRIN) which we have recently shown is altered by perturbing lens physiology. In order to study the changes of GRIN with aging, we have constructed a laser ray-tracing system to allow us to measure the optical properties of organ cultured lenses, while manipulating the underlying physiology of the lens. Our present system design includes two Single Reflex Lens (SLR) cameras and a highly precise illumination stage, which has enabled us to introduce the laser beams onto the lens at any desired angle and off-center offsets. Our current setup has laser beam angle measurement accuracy of ±0.2Ëš and image acquisition in-plane resolution of 30μm and pixel back-projection error of less than 0.3 of a pixel size. Also, our current calibrated setup is capable of measuring lens surface profile to an accuracy of <40µm, using SLR cameras which we have validated using in-vitro topography measurements from a number of bovine lenses. We have also implemented a BIONKO customized incubation chamber to control and manipulate the physiology and accommodative state of the imaged lens. By precisely controlling the laser beam delivery and tracing its path through the lens, mapping the lens’s surface profile while controlling its physiological and mechanical states, we are studying the effects of aging on the lens’ optical properties.