Document Detail


Perceptual efficacy of electrical stimulation of human retina with a microelectrode array during short-term surgical trials.
MedLine Citation:
PMID:  14638739     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: This work is part of a feasibility assessment of a retinal prosthesis as a means to restore vision to patients with blindness caused by retinitis pigmentosa. The primary goal was to assess the concordance of the form of induced perception and the pattern of electrical stimulation of the retina, and the reproducibility of the responses. METHODS: Five volunteers with severe retinitis pigmentosa and one with normal vision were studied. A companion paper in this issue provides details on demographics, visual function, surgical methods, general stimulation strategy, and data analysis. Volunteers were awake during surgery while a 10-microm-thick, microfabricated electrode array was placed on the retina. The array was connected to extraocular current sources that delivered charges to 50-, 100-, and 400-microm-diameter electrodes. Negative control trials were randomly included. Perceptual quality was judged by the similarity between the form of stimulation and perception (i.e., accuracy) and the reproducibility of responses. RESULTS: Only 1 of 40 control tests yielded a false-positive result. On average, volunteers 3, 5, and 6 reported percepts that matched the stimulation pattern 48% and 32% of the time for single- and multiple-electrode trials, respectively. Two-point discrimination in the best cases may have been achieved in two blind subjects using (center-to-center) electrode separation of 600 and 1960 microm. Reproducibility was achieved 66% of the time in the blind subjects. By comparison, in the normal-sighted subject, perceptual form was reported accurately 57% of the time, with 82% reproducibility, and two-point discrimination may have been achieved in one trial with 620-microm electrode spacing and in two trials each with 1860- and 2480-microm electrode spacing. In subjects 5 and 6, perceptual size was inconsistently related to the charge, although relatively large differences in charge (median: 0.55 microcoulombs [microC]) between two trials produced differently sized percepts. Longer stimuli did not produce rounder percepts. CONCLUSIONS: Single percepts induced by single-electrode stimulation were relatively small, but the form of percepts, especially after multielectrode stimulation, often did not match the stimulation pattern, even in a normal-sighted volunteer. Reproducible percepts were more easily generated than those that matched the stimulation pattern.
Authors:
Joseph F Rizzo; John Wyatt; John Loewenstein; Shawn Kelly; Doug Shire
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  44     ISSN:  0146-0404     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-11-25     Completed Date:  2003-12-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5362-9     Citation Subset:  IM    
Affiliation:
Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA. joseph_rizzo@meei.harvard.edu
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Blindness / etiology,  physiopathology*
Electric Stimulation / methods
False Positive Reactions
Female
Humans
Male
Microelectrodes
Middle Aged
Predictive Value of Tests
Reproducibility of Results
Retinaldehyde / physiology*
Retinitis Pigmentosa / complications,  physiopathology*
Sensory Thresholds / physiology*
Visual Perception / physiology*
Chemical
Reg. No./Substance:
116-31-4/Retinaldehyde

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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