Abstract
Purpose :
Intracortical visual prostheses (ICVPs) generate a phosphene map in wearers’ visual fields. Three modalities, finger pointing, eye movement, and head movement, are tested for reconstructing ICVP patients’ phosphene map, but each may have considerable distortion. The distortion may be reduced by scaling the simulated phosphene map obtained from each of the above modalities.
Methods :
Normally sighted participants were shown a set of 32 dots (“phosphenes”) in the central 35° of the lower-left visual field quadrant, one by one, in a VIVE Pro Eye headset. Participants indicated the location of the phosphene by finger-pointing, eye movement, and head movement. Finger positions were collected in two conditions: finger-eye and finger-head. Each condition was repeated three times. Polhemus G4 trackers recorded finger positions and head movements. Eye movements were recorded using the VIVE Pro Eye built-in tracking feature. Data analysis was performed through shifting and scaling the clusters of obtained dots to equate their centers of mass and dispersions to those of the original phosphenes.
Results :
Across all obtained data, the average scaling factor for eye maps, finger maps, and head maps are 0.75(±0.18), 0.41(±0.11), and 0.60(±0.17), respectively. The average distances between scaled dots and original phosphenes in eye, finger, and head maps were 1.56°, 1.71°, and 2.53°, respectively. Thus, similar scaling factors were observed across subjects for all three settings; eye position and finger movement had better accuracy and precision than head movement.
Conclusions :
Since the three scaling factors are similar across sighted subjects, we can apply these factors to blind subjects’ data. Furthermore, the scaled phosphenes were close to the original ones, so we can expect the scaled phosphenes to be sufficiently accurate for image presentation in blind subjects.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.