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Optimisation des optiques bifocales destinées à la correction de la presbytie

Abstract : Giving the aging of the population, and therefore the augmentation of presbyopes, the improvement of optics used to compensate for this visual impairment are at stake. We optimized bifocal optics designs, which only have two powers: one dedicated to distance vision and one dedicated to near vision. For this, we simulated images as they would appear through our designed optics, and asked subjects to grade the quality of these simulated images. First study dealt with the ratio of area optimizing visual quality at distance and at near. The best results were obtained for a ratio of 40% of central near vision, even if values from 20 to 50% gave quite comparable satisfying results. However, these 2 zone optics have a drawback they are very sensitive to the change of pupil diameter, which happens very often. A change in pupil size leads to a change of ratio of areas, the solution consists in using several concentric zones alternating between distance and near correction. The second study was about the optimization of the number of concentric zones in these bifocal optics using the same method. When the number of zones is increased enough, interferences allow to improve intermediate visual quality, as our profiles are built as Fresnel networks. Five zone profiles give a good distance and near vision with a little intermediate vision, and 8 zone profiles give an acceptable quality of vision from far to near. These profiles were evaluated in more realistic conditions, in presence of aberrations, decentration and different pupil diameters by two populations with different age. The age of subjects did not influence their evaluation of the optics. Aberrations had more impact on visual quality than decentration. Pupil diameter had a stronger influence on the optics with less number of zones. Eventually, we compared our optimized profiles with actual contact lenses available on the market. When looking at visual quality and depth-of-focus, our profiles were better than the ones available on the market. Therefore, it would be interesting to make prototypes to try them on real subjects. The designs developed in this work could be used to personalize presbyopes optical compensation. Different designs could be tried on each eye, allowing to combine two profiles per subject. A lot of inter-individual variations, also observed in previous studies, remain unpredictable. They could be linked to differences in contrast sensitivity or tolerance to blur. It would be interesting to create a visual test consisting in evaluating blurred images, in order to predict of a subject is a good candidate to fit with bifocal optics.
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Submitted on : Wednesday, October 12, 2016 - 3:27:10 PM
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David Rio. Optimisation des optiques bifocales destinées à la correction de la presbytie. Optique [physics.optics]. Université Paris Saclay (COmUE), 2016. Français. ⟨NNT : 2016SACLS231⟩. ⟨tel-01380151⟩

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