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Alex Zlotnik, Shai Ben Yaish, Oren Yehezkel, Michael Belkin, Zeev Zalevsky; Thin films as spectacles and contact lenses for aberration-corrected vision via brain adaptation to contrast. Journal of Vision 2008;8(6):263. doi: 10.1167/8.6.263.
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© ARVO (1962-2015); The Authors (2016-present)
Our aim was to develop special spectacles and contact lenses capable of solving common refractive errors such as myopia, hyperopia and regular and irregular astigmatism, as well as other accommodative insufficiency states (e.g., presbyopia), by exploiting brain's capability to adapt to contrast. Normally, these refractive errors are treated with adjusting a refractive correction. The method we used was adapting a special all-optical extended depth of focus concept taken from digital imagery. Special thin phase-only binary mask containing annular-like spatially large structures was developed to provide extension of the focus depth. This creates a “funnel” in the retina plane that is insensitive to defocus. The image is shown with no reduction of the spatial spectral content but with a reduction of the imaging contrast. Due to brain adaptation, the contrast reduction is corrected and brought into the normal (standard) range. Here we present experimental bench results as well as preliminary clinical trials. The clinical testing included measuring the visual acuity under different illumination conditions (pupil size varied from 2 to 4 mm), as well as stereoscopy, color vision and contrast sensitivity. In the optical bench, the optical element showed an extension of 2.5 Diopters. In the clinical tests, we found an improvement of up to 3 Diopters in presbyopic subjects for pupil sizes of 2 to 4 mm and improvement of more than 2 Diopters for regular and irregular astigmatism. The high-level performance of the proposed element, including the high contrasted quality vision is obtained due to the brain contrast adaptation capability since similar element in a digital imaging system exhibited visible reduction in contrast.
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