Perceptual learning : a novel method to improve the near reading abilities in early stage presbyopia patients

Objective: This study aims to investigate the effects of perceptual learning in subjects with early stage presbyopia. Methods: Forty subjects (40 eyes) with presbyopia were recruited and divided into two groups, randomly. Treatment group received practice with perceptual learning software. Another group was allocated to the blank control group. Reading acuity, maximum reading speed, critical print size, and central lens thickness changes in amplitude of accommodation were measured using the reading visual acuity chart and the AS-OCT (Anterior Segment Optical Coherence Tomographer) for each subject at five time points: before treatment and at 3, 6, 9 and 12 weeks during the perceptual learning treatment. Functional magnetic resonance imaging (fMRI) data were acquired for treatment group twice: before and after 12 weeks of perceptual learning treatment. Results: After 12 weeks treatment, the treatment group achieved a mean improvement from 5.15±1.10 pt (point) to 3.95±0.75 pt in reading acuity (F = 22.92, P<0.05); a mean improvement from 317.07±33.29 w/m (words per minute) to 324.70±31.89 w/m in maximum reading speed (F = 4.83, P<0.05); a mean improvement from 18.43±3.22 pt to 14.73±2.76 pt in critical print size (F = 29.39, P<0.05). Central lens thickness changes in amplitude of accommodation were little changes in treatment group, from 0.0429±0.0124 mm to 0.0428±0.0125 mm (F = 0.79, P = 0.38). The control group did not show any significant change in reading acuity, maximum reading speed, critical print size, and central lens thickness changes in amplitude of accommodation. Comparisons of treatment and control groups revealed statistical differences in reading acuity, maximum reading speed, and critical print size (F = 30.34, F = 4.55, F = 41.49, all P<0.05), which interacted between two factors (time × groups), but central lens thickness changes in amplitude of accommodation was not found statistically differences (F = 1.06, P = 0.31). Increased activation via presbyopic eyes was found in BA (Brodmann Area) 17-19, left fusiform gyrus, lingual gyrus and right occipital gyrus, cuneus, after the perceptual learning treatment. Conclusion: Our findings suggest that perceptual learning can improve the near reading abilities in patients with early stage presbyopia and the improvements are not due to the changes of lens, rather, it is likely to rely on the plasticity of BA 17-19.