Abstract
Purpose :
This study analyzes postoperative changes in the position of the Argus II Retinal Prosthesis’s electrode array over a two-year period. It specifically assesses the presence or absence of linear implant movement and/or angular rotation around the axis of the implant tack over time, and evaluates any correlation that such movement had with postoperative visual function tests.
Methods :
This is a single center, single surgeon cohort study that enrolled five patients with implantation of Argus II Retinal Prosthesis at Stony Brook University Hospital. Fundoscopy was performed at each postoperative follow up visit at month 1 (M1), month 3 (M3), month 6 (M6), month 12 (M12), and month 24 (M24). Visual function data (Direction of Motion (DOM) and Square Localization (SL)) from each visit was extracted from the Argus II Retinal Prosthesis Post Approval Study. Fundoscopy images were extracted and analyzed via NIH ImageJ. Data analysis was completed using IBM SPSS.
Results :
The angle of the implant with respect to the horizontal (Δ) showed a statistically significant increase from both M1 to M6 and M1 to M24 (paired t-test, p<0.05). The optic disc-tack-surgical handle angle (β) showed a significant increase from both M1 to M12 and M1 to M24 (paired t-test, p<0.05). The linear distance from the optic disc to the surgical handle on the implant (AB) significantly increased between M1 and M12 (paired t-test, p<0.05). There were significant negative correlations between length AB and SL (r = -0.582, p<0.01) and DOM (r = -0.0753, p<0.01), between angle β and SL (r = -0.725, p<0.01) and DOM (r = -0.459, p<0.05), and between angle Δ and SL (r = -0.615, p<0.01). Based on multivariate regression analysis, angle β, angle Δ, and length AB were significant predictors of SL outcome (p<0.000) and angle β, angle Δ, length AB, and length AC were significant predictors of DOM outcome (p<0.01).
Conclusions :
This study demonstrates that there is both statistically significant linear implant movement and angular rotation around the axis of the implant tack over time and that this movement had negative effects on visual function outcomes. It is important, moving forward, to take this into consideration when designing retinal implants, so that the implant’s efficacy is not affected by such anatomic changes.
This is a 2021 ARVO Annual Meeting abstract.