Investigating Keratoconus Using Optical Eye Modeling

Keratoconus (KC) is a corneal atrophy which causes a conical extrusion (cone). It is often misdiagnosed as optical defocus with astigmatism. In this thesis, computer KC eye models for various conditions are constructed. Using the KC eye model the influence on visual performance including the consequent refractive errors and the higher-order aberrations of KC eyes was investigated. The affects of cone shape, dimension (volume), and location on visual performance are also discussed. The modeled KC eyes are additionally used to evaluate the performance of a common eye vision-screening instrument. The simple photorefraction (PR) technique uses only one small light source with a camera to photograph ocular reflection patterns. Computer optical ray tracing was performed to simulate the PR images of both KC eyes and astigmatic eyes. The simulation results shown indicate the ability to detect and differentiate KC from normal refractive errors.