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S. T. L. Chung; The Feasibility of Enhancing Reading Performance in People With Central Vision Loss Through Perceptual Learning. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3631.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning has been shown to be effective in improving visual functions in adults who are well past the critical period for visual development, including adults with amblyopia. The goal of this study was to evaluate the feasibility of applying perceptual learning to improving reading performance in people with long-standing central vision loss.
Five observers with long-standing central vision loss (age: 57-85, logMAR acuity: 0.46-1.12) were trained on an oral sentence reading task (8-14 words per sentence), with words presented one at a time using rapid serial visual presentation (RSVP). Reading speed was defined based on the RSVP word exposure duration that yielded 80% of the words read correctly. A pre-test consisted of measurements of high-contrast visual acuities, RSVP reading speed for a range of print sizes from which the critical print size for reading was determined, the location of the preferred retinal locus (PRL) and fixation stability as assessed using a scanning laser ophthalmoscope. Training consisted of six weekly sessions of RSVP reading at a print size equivalent to 1.4x the critical print size. Each training session lasted 1.5-2 hrs, and comprised 10 blocks of trials with 30 sentences per block. A post-test, identical to the pre-test, followed the last training session.
Over the course of training, all observers showed a steady improvement in their RSVP reading speed, with the fastest rate of improvement occurring during the first two training sessions. Across observers, the overall improvement in reading speed averaged 55% (range: 32-75%). Comparisons of pre- and post-test measurements revealed very little changes in visual acuity, critical print size, the location of the PRL and fixation stability.
The specificity of the learning effect, and the lack of any changes to the location of the PRL and fixation stability suggest that the observed improvements following training are not due to a general improvement in observers’ ability to deploy attention, the adoption of a retinal location with better visual capability, or an improvement in the oculomotor system. Rather, the improvements are likely to represent genuine plasticity (the capability to improve) of the visual system despite the older ages of our observers, coupled with long-standing sensory deficits. Our results suggest that perceptual learning might be an effective way of enhancing visual performance for people with central vision loss.
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