ABSTRACT NUMBER - S1209

SUB-RETINAL CHIP IMPLANTATION TO PARTIALLY RESTORE VISION IN ADVANCED RETINITIS PIGMENTOSA: UPDATE FROM THE OXFORD RETINAL IMPLANT ALPHA AMS TRIAL.


Thomas Edwards, Charles Cottriall, James Ramsden, Matthew Simunovic, Kanmin Xue, Eberhart Zrenner, Robert MacLaren

Meeting:  2017 RANZCO


SESSION INFORMATION

Date:      -

Session Title: Rapid Fire Presentations - Retina

Session Time:      -

Purpose: To assess the safety and efftcacy of a sub- retinal electronic implant in end-stage retinitis pigmentosa. Methods: The Retina Implant Alpha AMS (Retina Implant AG, Reutlingen, Germany) was implanted into six participants in an ongoing prospective clini- cal trial sponsored by the University of Oxford. Inclusion criteria included vague non-localizing or no light perception in the implanted eye and prior normal distance and reading vision. A range of func- tional outcome measures was assessed including monitor and table-based tests.
Results: All six participants underwent subretinal implantation with follow up periods ranging from 1-12 months. Light perception, temporal resolution and light localization was improved by the implant in all but one participant (P4) in whom the chip was not functioning optimally. The best grating acu- ity recorded for P1, P2, P3, P5 and P6 was 0.33, 1.0, 0.1, 0.33 and 0.1 cycles/degree respectively. The best-recorded number of high contrast objects cor- rectly located on a table was 3.2 and 0.5 with implant on vs off respectively (mean value; max. 4). All but P4 reported a subjective improvement in activities of daily living. The implant was removed from P3 after three months due to damage to the laminate insulation during a surgical revision, with a resulting loss of function. A retinal detachment occurred in the implant eye of P2 at 9 months, but reattachment surgery was performed without dis- turbing chip position.
Conclusions: The Retina Implant Alpha AMS improved visual performance in 5 of 6 participants and has exhibited improved functional longevity. Although implantation surgery remains challenging, new developments such as intra-operative OCT add reftnements to the surgical technique.

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