Development of a Full Pupilar Stiles-Crawford Function for Improved Visual Testing and Refractive Optics DesignSummaryThe human eye has three main optical elements: the cornea, the crystalline lens, and the retina. Current optical design for lenses and spectacles considers essentially only the refractive properties of the cornea and lens while ignoring essential optical mechanisms of the retina. This is most apparent in the Stiles-Crawford function that essentially reduces the visibility of light entering near the pupil rim to about 25% and thereby also diminishing the visual deterioration caused by intraocular scattering. The Stiles-Crawford effect, being of retinal origin and related to waveguiding mechanisms by individual photoreceptors, has hitherto not been adequately considered in the design of refractive optics and intraocular lenses but rather as an ad-hoc addition with a constant characteristic directionality factor if considered at all.In most eye model studies (such as used when designing refractive optics including contact lenses, spectacles, and intraocular lenses) the retina is typically considered as a passive screen but the photoreceptor structure as evidenced by the Stiles-Crawford effects are direct evidence of the need to consider the retina as yet an active optical element of the eye on line with the cornea and the crystalline lens for improved understanding of vision and future refractive optics design.Establishing a proper and validated procedure for characterizing the Stiles-Crawford effect both spatially and spectrally and, subsequently, developing a suitable mathematical description that will allow it to be incorporated in visual optics simulations and future refractive optics designs will be the main goal of this research project. Upon completion, it is expected to facilitate a major leap forward in terms of obtainable visual quality in the refraction-corrected eye and to be implemented in future Alcon Research developed intraocular lenses. Indeed, a proper Stiles-Crawford-compensated intraocular lens is expected to approximately double the visual acuity obtainable for a 5 mm pupil as compared to a more conventionally-designed lens.Benjamin Lochocki,School of Physics, Advanced Optical Imaging Group, University College Dublin