Abstract
Purpose :
The visual reconstruction by means of retinal prostheses requires evoking pseudolight sensations (phosphene) by electrical stimulation. However, change in electrode position over time [P. J. Allen, et al. IOVS 2019;60:4983, Y. Terasawa, et al. IOVS 2017;58:4195] makes it difficult to evoke phosphene. In this study, we evaluated whether an electrode array including dorsal protrusions (spike-shaped array; Fig. 1) can reduce the movement of the electrode.
Methods :
A control array without dorsal protrusions or a spike-shaped array were implanted in the scleral pocket of rabbits (n = 6). Both arrays had platinum electrodes (diameter; 0.5 mm, height; 0.3 mm). The electrode positions were observed by scanning laser ophthalmoscopy (SLO) images immediately after surgery, and 1 week and 1 month postoperatively. The movement of the electrodes was compared by superimposing the SLO images using the coagulation plaques or black dots around the optic nerve papilla as reference points. All procedures were in accordance with the Association for Research in Vision and Ophthalmology Statement for the Use of Animals in Ophthalmic and Vision Research. This study was approved by the Institutional Animal Care Committee of Nidek Co., Ltd.
Results :
SLO imaging showed movement of the device, the control array shifted a mean of 0.20 ± 0.05 mm (n = 4) and the spike-shaped array shifted a mean of 0.12 ± 0.07 mm (n = 6) between the immediate postoperative period and the first postoperative week (p = 0.07, independent t-test). The control array shifted a mean of 0.37 ± 0.06 mm (n = 4) and the spike-shaped array shifted a mean of 0.23 ± 0.10 mm (n = 6) between the first postoperative week and the first postoperative month (p < 0.05, independent t-test).
Conclusions :
The spike-shaped array had a smaller movement distance of the electrodes than the control array. It is speculated that the connection between the tissue and the protrusions become stronger with elapsed time after the surgery. These results suggested that using the spike-shaped array was effective as a countermeasure against the shifts in electrode position.
This is a 2021 ARVO Annual Meeting abstract.