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Thomas L Edwards, Charles L Cottriall, Matthew P Simunovic, James D Ramsden, Eberhart Zrenner, Robert E MacLaren; Preliminary Findings from the Oxford Retinal Implant Alpha AMS Trial. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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To assess the safety and efficacy of a subretinal electronic implant in end-stage retinitis pigmentosa. Visual function with the device was assessed in an ongoing prospective, participant-masked, clinical trial based at the University of Oxford.
The Retina Implant Alpha AMS (Retina Implant AG, Reutlingen, Germany) was implanted into one eye of three participants with end-stage retinitis pigmentosa. Inclusion criteria included vague non-localizing or no light perception in the eye receiving the implant, intact inner retinal function and previous reading visual acuity for a minimum of 12 years. Functional outcome measures included 1) screen-based standardized 2- or 4-alternative forced-choice tests of light perception, temporal resolution, light localization and grating acuity; 2) greyscale discrimination; 3) localization of high contrast objects; 4) full field stimulus threshold (FST) and 5) visual experiences during outdoor and daily-life activities.
To date (3-6 months follow up), light perception, temporal resolution and light localization was improved by the implant in all three participants. The best grating acuity recorded for P1, P2 and P3 was 0.33, 1.0 and 0.1 cycles/degree respectively. The best recorded number of high contrast (white on black) objects correctly located on a table was 4 and 1 with implant on vs off respectively (mean value; max. 4). Similarly, for high contrast tableware the number of items located was 3.7 and 0 for implant on vs off respectively (mean value; max. 4). Two of seven greyscale values were presented side by side on a split screen. Overall discrimination between the two sides was greater with the implant on vs off. An implant-mediated FST was detected in P2 (absent with implant off) and was improved in P1 from 14.8 dB (off) to 10.1 dB (on). All three participants reported a subjective improvement in activities of daily living. These results were sustained at the most recent study visit. However, in one participant (P3) an extra-ocular component of the device eroded through conjunctiva three months post implantation and was damaged by subsequent surgical revision, with a resulting loss of function. No serious adverse events have been reported thus far in any participant.
Short-term results indicate that the Retina Implant Alpha AMS is reliable, well tolerated by patients and improves their visual function.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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