Neural Restoration Training improves visual functions and expands visual field of patients with homonymous visual field defects.

Abstract

In recent years, the introduction of visual rehabilitation for patients with homonymous visual field defects has been met with both enthusiasm and caution. Despite the evidence that restitutive training results in expansion of the visual field, several concerns have been raised. We tested the effectiveness of a new rehabilitative protocol called "Neuro Restoration Training" (NRT) in reducing visual field defects and in restituting visual functions in the restored hemianopic area. Ten patients with homonymous visual field defects (lesion age >6 months) where trained in detecting low contrast Gabor patches randomly presented in the blind field, which refers to regions of 0 dB sensitivity, and along the hemianopic boundary between absolute (0 dB) and partial blindness (>0 dB). Training included static, drifting, and flickering Gabors in different blocks. Positions along the hemianopic boundary were systematically shifted toward the blind field according to the threshold reduction during the training. Before and after the training, we assessed visual field expansion and improvement in different high-level transfer tasks (i.e., letter identification and shape recognition) performed in the hemianopic boundary and in the blind field. NRT led to significant visual field enlargement (≈5 deg), as indicated by the conventional Humphrey perimetry, and two custom made evaluations of visual field expansion with eye movement control (one static and one dynamic). The restored area acquired new visual functions such as small letter recognition and perception of moving shapes. Finally, for some patients, NRT also improved detection, either aware or not, of high contrast flickering grating and recognition of geometrical shapes entirely presented within the blind field. These results suggest that NRT may lead to visual field enlargement and translate into untrained visual functions.