‘Visual’ acuity of the congenitally blind using visual-to-auditory sensory substitution

Abstract

Sensory Substitution Devices (SSDs) convey visual information through sounds or touch, thus theoretically enabling a form of visual rehabilitation in the blind. However, for clinical use, these devices must provide fine-detailed visual information which was not shown yet for this or other means of visual restoration. To test the possible functional acuity conveyed by such devices, we used the Snellen acuity test conveyed through a high-resolution visual-to-auditory SSD (The vOICe). We show that congenitally fully blind adults can exceed the World Health Organization (WHO) blindness acuity threshold using SSDs, reaching the highest acuity reported yet with any visual rehabilitation approach. Preliminary findings of a neuroimaging study of a similar reading task using SSDs suggest the specific involvement of the congenitally blind visual cortex in processing sights-from-sounds. These results demonstrate the potential capacity of SSDs as inexpensive, non-invasive visual rehabilitation aids, as well as their advantage in charting the retention of functional properties of the visual cortex of the blind.