Abstract
Purpose :
The subretinal PRIMA implant can provide partial vision restoration with a maximum field of view of 7 degrees. This study assesses by psychophysical testing with healthy subjects whether the visual field offered by two adjacent PRIMA implants (2x2mm in size) at different distances translates into a significant impact on the reading comfort and reading speed versus with a single implant.
Methods :
The reading performance of sixteen normal-sighted volunteers was evaluated using four charts of the Bailey-Lovie test with a simulated minimized visual field to reproduce four reading conditions:
- One single implant (model 1)
- Two implants with no distance (model 2)
- Two implants separated by 0.5 mm (model 3)
- Two implants separated by 1 mm (model 4)
While reading, visual field limiters were employed to simulate the four implanted conditions: A4 opaque paper with one squared cutout, and two squared cutouts separated by 0 mm, 0.5 mm, and 1 mm respectively.
During the reading tests, the reading speed was measured, the number of misread words was recorded, and the subjective reading comfort was evaluated on a 1-10 scale.
For every parameter the median, mean, standard deviation, and p-values of the differences were calculated.
A mixed regression model was applied for reading time and comfort variables, whereas the error rate was generalized via a mixed logistic regression model.
Results :
Model 2 (two implants without distance) showed the highest reading speed, 13.68 s/line, i.e., 39% higher than single implant condition.
Additionally, the same model resulted as the one providing the highest reading comfort rate, 7.27/10, i.e., 40% higher than the single chip model.
Significant differences of 35% and 36% in reading speed were observed in model 3 and model 4 with respect to model 1.
No evidence of statistical difference in error rate was obtained by all multi-chip models.
Conclusions :
Although the used setup has some limitations, e.g., that subjects could freely move their focus on the presented visual field, it was demonstrated that the implantation of multiple implants can potentially improve the reading speed significantly.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.