Optical, Perceptual and Adaptational Implications of different Presbyopic corrections

Presbyopia Corrections: Optical, Perceptual and Adaptational Implications presented at the Universidad Complutense de Madrid, Spain. Presbyopia, the physiological inability of the aging crystalline lens to accommodate for objects at near distance, can be treated using a multitude of optical corrections. Systematic evaluation of the visual system's ability to interact with these corrections will help in optimization of their performance. In this thesis we studied optical and perceptual performance of different presbyopic corrections such as alternating vision, monovision and simultaneous vision and the effect of adaptation on perceptual performances. We used custom-developed adaptive optics setup to measure and correct ocular aberrations and projected manipulated images simulating pure simultaneous vision corrections of different far/near energy profiles and near additions. We also developed and validated an on-bench and a hand-held simultaneous vision simulator to optically simulate pure or segmented simultaneous vision corrections. Psychophysical methods were employed to study the changes in perceptual quality and after-effects of adaptation. We performed numerical simulations to predict perceptual performance from the ocular aberrations of the subjects. We demonstrated that mechanism of adaptation to simultaneous vision is similar to that of blur adaptation, influenced mostly by retinal image contrast and that systematic changes in visual and perceptual performance influenced by multifocal design and testing distance. The ocular optics of the subject's eye correlated significantly with visual performance and was associated with the intersubject variability in performance. We found that a cyclopean locus for perception and adaptation, in subjects with different blur magnitude between eyes, influenced by the eyes with better optical quality. The internal code for blur was also influenced by the eye with better optical quality, both in orientation and magnitude. Our results confirm that the existing optical solutions should be chosen based on the subjective needs and the ocular optics would be an ideal starting point to customize optical solutions of presbyopia for optimal performance. We also demonstrated the usefulness of rapid assessment of perception to multifocal designs using the handheld, seethrough simultaneous vision simulator.