Geographic atrophy results in irreversible central vision loss, but, with acoustic biofeedback vision rehabilitation, patients with AMD can rehabilitate their visual function, a study recently found. Rehabilitation training involves optimizing healthy parts of the retina for visual fixation by reorganizing the primary visual cortex.
When central vision degrades, patients develop an eccentric fixation area, or a preferred retinal location (PRL), the researchers noted. The PRL is usually a healthy part of the retina found on the superior or horizontal meridian of the fovea. Previous studies have demonstrated that patients with central vision loss can develop multiple PRLs but may not know how to take advantage of them. Visual rehabilitation aims to show them how.
The prospective, non-randomized study included patients with advanced atrophic AMD younger than 90. The twice-weekly training lasted for five weeks. Patients sat in front of a pattern stimulator and were fit with a corrective lens over the eye with the highest best-corrected visual acuity for scotopic rehabilitation.
As part of their training, patients fixated on the stimulus target. During this process, “a stimulus from the optical pathways through the cortical visual areas is created and read by surface electrodes, which then produce a bioelectric visual evoked potential,” the researchers explained. Patients were instructed to fixate on a target using a retinal area, which produces a sound that grows more intense as the patient’s fixation improves. “The aim of the training is to ensure that the patient uses a retinal area with optimal biological activity,” the researchers said.
They concluded that their study suggests auditory biofeedback rehabilitation is a good method for improving low vision in AMD. “Our study confirms the evidence of the plasticity of the visual system that can be successfully trained to optimize residual vision, creating new connections between the retina and the visual cortex with a rearrangement of neurons in this area,” the study authors wrote in their paper.
Verdina T, Piaggi S, Ferraro V, et al. Efficacy of biofeedback rehabilitation based on visual evoked potentials analysis in patients with advanced age-related macular degeneration. Sci Rep. November 30, 2020. [Epub ahead of print].