Temporal processing in very low vision

Visual temporal frequency discrimination (TFD) capacities of four adults with very low vision (VLV) were assessed. Full-field flicker was generated by placing a 5×5 red LED array against a translucent eyepatch that served as a diffuser. Temporally modulated phase-randomized sine wave stimulus pairs (standard and test frequencies) were presented monocularly using a 2IFC procedure. Discrimination was tested at standard frequencies ranging between 0.75 and 57 Hz; TFD difference thresholds (?F) for the ten standard frequencies were estimated from maximum likelihood fits of Weibull functions. ?F was a constant or nearly constant proportion of F throughout the assessed range. These results show conclusively that TFD judgements can be rendered by those with simulated and actual VLV. Temporal coding of full-field light modulation has the potential to optimize a neglected sensory channel in individuals with VLV.