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Uri Polat, Anna Sterkin, Oren Yehezkel, Maria Lev, Ativ Zomet, Cliff Schor, Dennis Levi; Perceptual Training Overcomes the Optical Limits of Presbyopia. Invest. Ophthalmol. Vis. Sci. 2011;52(14):394. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning, prolonged practice of a visual task, can lead to improvement in visual function. In presbyopia, the visual input from the eye to the brain is limited by the optics of the eye. The purpose of this study was to ask whether perceptual learning in presbyopia leads to changes in optical functions in conjunction with the improvement in perceptual functions after training.
We have developed a structured perceptual learning method for improving visual functions in presbyopia. Subjects were trained on contrast detection of Gabor targets under backward masking conditions, posing temporal constraints on the visual processing. The training covered a range of spatial frequencies and orientations that were modified in accordance with the improvement of the subjects. The subjects were trained in a dark room from a distance of 40 cm with both eyes open. Visual acuity, spatial and temporal contrast sensitivity, contrast discrimination and reading speed were tested before and after the treatment. Front end aberrations, accommodation, depth of focus and pupil size were also measured before and after training. The subjects practiced for at least two sessions of about 30 min per week. The study was performed at the University of California, Berkeley, and included 25 presbyopic subjects (52.4 ± 0.88 years, mean ± se). Seven young subjects (23.4 ± 1.4 years, mean ± se) served as control group.
We found significant improvements in spatial and temporal contrast sensitivity, contrast discrimination and reading speed. After practice, perceptual functions reached the level of the young group. Visual acuity improved by ≈ 81% (2.57 ± 0.03 ETDRS lines, mean ± se), equivalent to a decrease in effective age of about 8 years. Processing speed improved as well. Moreover, after training, there was a real benefit for the subjects; many were able to read with no reading glasses. No changes in accommodation, and pupil size were found. Other optical functions will be reported as well.
Perceptual learning produced substantial improvements in contrast detection, contrast discrimination and reading speed. The results are consistent with our previous studies in presbyopic and young subjects, and are not a result of improved optical functions. Thus, our method is effective in improving visual functions in people with blurred vision by enhancing the image representation in the brain.
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