Exploring Relationship between Near Phoria, Reading Speed, Comprehension and Effect of Vision Therapy: A Systematic Review

Abstract

Aim:  To evaluate the relationship between near phoria and reading speed, comprehension and to assess the effectiveness of vision therapy.

Method: A comprehensive review of research papers investigating the effects of near phoria on reading performance was conducted. The studies involved utilized various research designs, including randomized controlled trials, observational studies, cohort studies, and case-control studies. Consistently used Binocular Vision tests used in the studies included the cover test, near point of convergence, positive and negative fusional vergence, vergence facility, accommodative facility, and stereopsis assessment. Reading performance was assessed using tools such as the Wechsler Individual Achievement Test (WIAT-III), Gates-MacGinitie Reading Test (GMRT), AIMSweb Reading Curriculum-Based Measure (R-CBM), and International Reading Speed Text (IReST). Selective Vision therapies  included office-based vergence/accommodative therapy, home-based exercises, prism therapy, and computer-based visual training programs to improve convergence and accommodation.

Results and Conclusion: The findings ruled-out a significant negative correlation between near phoria and reading performance. Individuals with binocular vision anomalies displayed slower reading speeds, increased fixation durations, and reduced comprehension compared to those with normal BV (p < 0.05). Studies indicate that convergence insufficiency and accommodative dysfunction contribute to ineffective reading, characterized by frequent reversions and loss of place while reading. Vision therapy such as vergence and accommodative exercises, prism therapy, and computer-based training, have shown improvements in reading fluency and eye coordination; however, their direct effect on comprehension is still inconclusive. Existing gaps in studies include insufficient studies on the sustained impact of therapy, the academic consequences of near phoria, and to standardize evaluation methodologies for reading and comprehension. Acknowledging these gaps will enhance understanding and optimizing vision therapy for improved reading outcomes