Biofeedback rehabilitation in patients with binocular inhibition due to macular disease

Abstract

Background: To investigate whether patients with binocular reading inhibition due to central vision loss benefit from a new biofeedback (BF) rehabilitation method that aimed at improving fixation stability and at establishing a correspondence between the monocular preferred retinal loci (PRLs) on functioning retina in both eyes. Methods: Thirty-three patients with bilateral macular disease and with binocular reading inhibition participated in 10 training sessions consisting of 10-min visual stimulation for each eye to stabilize fixation and relocate the PRL (if needed) using the BF module of the MP-1 microperimeter (Nidek Technologies Srl., Vigonza, PD, Italy). Binocular and monocular reading performance, contrast sensitivity, and visual acuity were evaluated pre and post training. Binocular summation/inhibition was evaluated with binocular ratio (BR). Results: Fixation stability improved significantly post training in both eyes. Maximum reading speed during binocular viewing increased from 57 ± 24wpm pre training to 67 ± 24wpm post training. BR increased for all parameters of reading, visual acuity, and contrast sensitivity. Training resulted in a complete reversal of binocular reading inhibition in 30% of patients. Conclusions: For patients with binocular inhibition due to central vision loss, BF training to stabilize fixation and to bring the monocular PRLs into correspondence on functioning retina in both eyes is an efficient rehabilitation method to improve binocular performance.