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G.N. Scarlatis, R.J. Greenberg, J.W. Judy; Performance of Low–Vision Activities of Daily Living Using Retinal–Prosthetic Simulation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3469.
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© ARVO (1962-2015); The Authors (2016-present)
This study explored the effects of resolution and grayscale of simulated prosthetic vision on the performance of low–vision activities of daily living (LVADLs).
Twenty participants with 20/30+ visual acuity performed nine independent LVADLs under nine different visual states (normal; video; simulated retinal–prosthetic vision at resolutions of 4×4, 8×8, 6×10, 16×16, 32×32, and 64×64; and blind) and three grayscales (2, 8, and 256). The LVADLs tested were reading newspaper headlines, typed letters, accounts and packet labels; recognizing faces; writing checks; and telling the time on a wrist watch, wall clock, digital display. After training, each subject completed each task under each visual condition in a random order determined by a customized computer program written in C++. Performance was recorded as subjective scores (0–4, with ≥3 considered successful) based on preset criteria for each task and the time required to complete each task.
In general, participants were unable to successfully complete tasks at the blind or low–resolution settings and successfully completed tasks at the high–resolution settings. Success rate varied at intermediate resolutions depending on the specific task tested. At 16×16 simulated resolution, >50% of participants were able to successfully complete most of the LVADLs tested and at 32×32 >50% of participants were able to successfully complete all of the LVADLs tested. Subjective performance mirrored and time to complete tasks inversely reflected the success rates.
A resolution of 16×16 or 32×32 pixels should provide useful vision that will enhance the quality of life of blind patients implanted with sight–restoring devices meeting these minimum specifications. Grayscaling did not appear to play a significant role in performance outcomes between 8 and 256 levels of grayscale, indicating that a processor transmitting 8 levels of stimulation to implanted electrodes should provide functional utility that rivals that of 265 levels of stimulation.
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