Optical aberrations of human eyes and their impact on visual performance

Purpose. The ultimate goal of optometric practice is to provide the best vision for patients. Although the current clinical routine to correct defocus and astigmatism of human eyes gives satisfactory visual acuity for most patients, the eyes with abnormal optics (e.g. dry eye, keratoconic eye, eye after laser refractive surgery and cataract eye) experience blurred retinal images even with the best spectacle corrections. The sub-normal visual performance is very often due to the existence of optical aberrations in the human eye. The accurate quantification of optical aberrations of human eyes will lead to the potential applications of correcting aberrations just as we do for defocus and astigmatism and therefore provide the human eye with ideal image quality. Methods. I developed Shack-Hartmann wavefront sensor (SHWS) and its data analysis software by myself. I used this laboratory SHWS to measure wavefronts coming out of human eyes. Results . For the first time in the literature, I demonstrated the feasibility to quantify the optical aberrations of pathological eyes and the clinical applications of using the SHWS to monitor the optical outcomes of corneal surgeries (corneal transplantation and laser refractive surgery). I used the wavefront sensing technology to evaluate the optical performance of contact lenses. Our novel works on contact lens evaluation provided valuable methodology and technology to improve optical design of contact lenses. I further studied the population statistics of optical aberrations of human eyes, the contributions of the cornea and the internal optics of the human eye on optical aberrations and the impact of monochromatic aberrations on vision. These three studies on a large population explored the nature and the impact of the optics of human eye and are the most comprehensive and complete studies in the field. Conclusion. My studies help to understand the nature of the optics of human eyes and guide the practice of correcting optical aberrations of the human eye in order for patients to have much better vision acuity than 20/20.