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Br J Ophthalmol. 2013 May;97(5):632-6. doi: 10.1136/bjophthalmol-2012-301525. Epub 2013 Feb 20.

The Argus II epiretinal prosthesis system allows letter and word reading and long-term function in patients with profound vision loss.

Author information

1
NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK. Lyndon.dacruz@moorfields.nhs.uk

Abstract

BACKGROUND:

Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, long-term retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life.

METHODS:

We report a prospective, internally controlled, multicentre trial of the Argus II system. Twenty-eight subjects with light perception vision received a retinal implant. Controlled, closed-group, forced-choice letter identification, and, open-choice two-, three- and four-letter word identification tests were carried out.

RESULTS:

The mean±SD percentage correct letter identification for 21 subjects tested were: letters L, T, E, J, F, H, I, U, 72.3±24.6% system on and 17.7±12.9% system off; letters A, Z, Q, V, N, W, O, C, D, M, 55.0±27.4% system on and 11.8%±10.7% system off, and letters K, R, G, X, B, Y, S, P, 51.7±28.9% system on and 15.3±7.4% system off. (p<0.001 for all groups). A subgroup of six subjects was able to consistently read letters of reduced size, the smallest measuring 0.9 cm (1.7°) at 30 cm, and four subjects correctly identify unrehearsed two-, three- and four-letter words. Average implant duration was 19.9 months.

CONCLUSIONS:

Multiple blind subjects fitted with the Argus II system consistently identified letters and words using the device, indicating reproducible spatial resolution. This, in combination with stable, long-term function, represents significant progress in the evolution of artificial sight.

PMID:
23426738
PMCID:
PMC3632967
DOI:
10.1136/bjophthalmol-2012-301525
[Indexed for MEDLINE]
Free PMC Article

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