Analysis of three postoperative morphological parameters after epiretinal prosthesis implantation: Array-to-retina distance, array rotation and development of fibrotic tissues, and their influence on visual function recovery ; Analyse de trois paramètres morphologiques postopératoires après implantation d'une prothèse épirétinienne : distance entre la matrice et la rétine, rotation de la matrice et développement des tissus fibreux, et leur influence sur la récupération de la fonction visuelle

Argus II is the most implanted prosthesis when considering gaining sight in advance retinal dystrophy. The purpose of this study is to describe and evaluate the long term evolution of the implanted array position and how it is related with some of the post- operative tissue healing factors. Eighteen consecutive patients with end-stage retinitis pigmentosa were analyzed in this single-arm prospective multicenter clinical trial between November 2014 and June 2016. Postoperative data at day 1, weeks 1 and months 1, 3, 6, 12 and 24 were collected. Postoperative array-retina distance and development of fibrosis were measured on spectral-domain optical coherence tomography images. Position of the array was evaluated on fundus images between months 1 and 24. Visual function was analyzed using three Argus II designed tests; square Localization, direction of motion and grating visual acuity. Main outcome measures: evaluation of postoperative tissue healing fibrosis development and its influence on functional vision performances. Considering the array-to-retina distance over time, no variation of the global median value at month 1 (93, 1µm; interquartile range (IQR) : 23,7; 385,9) and month 24 (126,9 µm; IQR: 0; 272,8) was observed (p=0,82). A significant rotation of the device through time was observed, however not linear as demonstrated by a quadratic function of time with a significant linear term (p= 0.0041) and quadratic term (p= 0.0299). A significant increase of fibrotic tissue was observed in 9 of the patients, here again, the evolution was not linear, as demonstrated by a quadratic function of time with a significant linear term (p= 0.0006) and quadratic term (p= 0.0003). No statistical significant variations of the angle was highlighted according to the presence/absence of fibrosis. (p=0,92). Better visual function results are observed when the system is ON in all three designed tests. This improvement is also put forward in the subgroups with fibrosis, for SL and DOM tests, compared to the subgroups of patients ...