Insertion of an epiretinal prosthesis for retinitis pigmentosa

The committee considered evidence from 7 case series that included a total of 129 patients. However, there is likely to have been considerable overlap between studies with patients taking part in more than 1 study.

In a case series of 30 patients implanted with an epiretinal prosthesis, improvements in visual acuity were reported in 23% (7/30) of patients at follow‑up of up to 2.7 years. Visual acuity improved from worse than 2.9 logMAR (logarithm of the minimum angle of resolution) to between 2.9 and 1.6 logMAR (p value not reported).

In the case series of 30 patients, patients were asked to locate a white square that randomly appeared on a black LCD touchscreen. Significantly better square localisation test results were reported in 96% (27/28) of patients when their prosthesis systems were switched on. No further details were provided.

In the case series of 30 patients, patients were asked to indicate the path of a white bar that swept across a black LCD touchscreen. Significantly better direction of motion test results were observed in 57% (16/28) of patients when their prosthesis systems were switched on. No further details were provided.

In the case series of 30 patients, patients were asked to stand in the centre of a room, or offset left of centre by 3 feet, or offset right of centre by 3 feet. They were asked to find a rectangular 'door' 20 feet away and to place their hand on it. The mean success rate was 60% when the prostheses were switched on compared against 5% when the prostheses were switched off, at 24‑month follow‑up.

In a case series of 6 patients, the mean percentage of successful grasps of a white cube placed on a black surface was 69% when prostheses were switched on compared against 0% when prostheses were switched off, at 3‑year follow‑up. There was no significant difference between the proportion of successful grasps when patients' eyes were 'patched' (both eyes taped closed) or 'unpatched'.

Specialist advisers listed key efficacy outcomes as improvement in vision (recognition of words or objects, as well as perception of light, movement or direction), performance in spatial or motor tasks and improved quality of life.