Efficacy of perceptual vision therapy in enhancing visual acuity and contrast sensitivity function in adult hypermetropic anisometropic amblyopia

BACKGROUND The purpose of this study was to evaluate the efficacy of neural vision therapy, also termed perceptual vision therapy, in enhancing best corrected visual acuity (BCVA) and contrast sensitivity function in amblyopic patients. METHODS This prospective study enrolled 99 subjects previously diagnosed with unilateral hypermetropic amblyopia aged 9-50 years. The subjects were divided into two groups, with 53 subjects (53 eyes) in the perceptual vision therapy group and 46 subjects (46 eyes) in the control group. Because the nature of the treatment demands hard work and strict compliance, we enrolled the minimal number of subjects required to achieve statistically significant results. Informed consent was obtained from all subjects. Study phases included a baseline screening, a series of 45 training sessions with perceptual vision therapy, and an end-of-treatment examination. BCVA and contrast sensitivity function at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies were obtained for statistical analysis in both groups. All subjects had follow-up examinations within 4-8 months. With the exception of one subject from the study group and two subjects from the control group, all subjects had occlusion during childhood. The study was not masked. RESULTS The results for the study group demonstrated a mean improvement of 2.6 logarithm of the minimum angle of resolution (logMAR) lines in visual acuity (from 0.42 to 0.16 logMAR). Contrast sensitivity function improved at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies. The control group did not show any significant change in visual acuity or contrast sensitivity function. None of the treated eyes showed a drop in visual acuity. Manifest refractions remained unchanged during the study. CONCLUSION The results of our study demonstrate the efficacy of perceptual vision therapy in improving visual acuity. The 2.6 logMAR lines improvement in visual acuity is encouraging, and is consistent with the results of previous studies. However, long-term follow-up and further studies are needed.