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Assessing the utility of visual acuity measures in visual prostheses
1Department of Applied Physics, Jerusalem College of Technology-Lev Academic Center, Jerusalem, Israel; Second Sight Medical Products, Inc., Sylmar, CA United States.
Vision Research
|February 1, 2015
Summary
Electrical stimulation via retinal prostheses can restore some vision. This study shows that measurable visual acuity indicates the brain is processing patterned visual information, not just brightness.
Area of Science:
- Neuroscience
- Ophthalmology
- Biomedical Engineering
Background:
- Clinical trials are developing retinal prostheses for visual impairment using electrical stimulation.
- Some patients with retinal implants report benefits in daily activities despite un-patterned visual perception, suggesting active scanning strategies.
Purpose of the Study:
- To determine if measured visual acuity accurately reflects patterned image perception from retinal prosthesis stimulation.
- To evaluate the conditions under which visual acuity indicates patterned vision.
Main Methods:
- Sighted participants used a pixelized simulator to experience "normal mode" (patterned vision) and "brightness mode" (non-patterned vision).
- Participants employed head scanning strategies to assess visual acuity under different stimulation conditions.
Main Results:
- Head scanning strategies improved acuity beyond static resolution limits in both modes.
- In "brightness mode," acuity was better than array resolution but worse than pixel density limits.
- In "normal mode," acuity exceeded the resolution limits of the simulated pixels.
Conclusions:
- Achieving visual acuity comparable to electrode resolution suggests perception of spatial patterns.
- This finding is crucial for interpreting visual prosthesis performance and patient feedback.
