Advanced Tomography in Optics of the Human Eye

Abstract

The eye is the most natural optical system available to us. Because of the eye, it is possible for mankind to inspect the world around us with evaluate motion, color and other details. The information obtained from the eye allows us to make decisions that range from menial to critical and even life-saving.

However the human visual system seems to lack perfection in adapting to new conditions and degrading vision. Aberrations are the major factors that affect the image quality of the eye. A large amount of lower order aberrations are found in the peripheral visual field and higher order aberrations altered in from the center to the peripheral in the visual field. Understanding the aberrations of the eye can help to learn more about the optical function of the eye. The aim of this study was to understand the optical function of the human eye by reconstructing the wavefront aberration of the eye and investigating the tomography of the optical elements of the eye.

The knowledge of vision, aberration, and the basic optics of the eye is introduced. A new ocular wavefront aberration measurement algorithm is investigated and compared with the other methods applied by the previous researchers.

The main aim is to investigate the optical function of the eye, particularly the crystalline lens. For this purpose, a complex model eye is designed with adjustable lens at both on- axis and off-axis field; a new computer based ray-tracing algorithm is applied to find the wavefront aberration and the refractive index profile of the lens of the eye. At the end, the wavefront aberration is reconstructed for the model eye, including those from different angles into periphery.

Another objective is to reconstruct the lens by applying tomography algorithms, in this thesis; a modified back projection algorithm is introduced and tested, from which the refractive index distribution of the lens can be reconstructed, however, at this stage, the reconstructing method still needs to be improved to gain a reliable refractive index distribution of the lens.