Long-term stimulation by active epiretinal implants in normal and RCD1 dogs.
An epiretinal prosthesis, consisting of an extraocular microelectronic stimulator and an intraocular electrode array, was implanted in one eye of three blind and three sighted dogs. Three dogs (2 blind, 1 normal) were stimulated for 120 days, and two dogs (both normal) for 60 and 103 days respectively for 8-10 h/day at levels of 0.1 mC cm(-2) and 0.05 mC cm(-2), with each stimulus level presented to half of the array. One blind dog was kept as an inactive implant control. During the study period, electroretinograms (ERG) and fundus photographs were recorded. At the end of the study period, the dogs were sacrificed and histological and morphometric evaluation was made of the retina. No inflammatory reaction, neovascularization or hemorrhage was observed during the follow-up examinations. ERGs were unchanged. Stimulus levels used were of sufficient amplitude to elicit cortical evoked potentials. Histological evaluation showed no inflammatory infiltrates or changes in retina morphometry related to electrical stimulation when compared to the unstimulated control eye. Morphometric analysis revealed no consistent differences relating to electrical stimulation. In summary, chronic electrical stimulation of the dog retina at up to 0.1 mC cm(-2) with an epiretinal prosthesis does not appear to adversely affect the retina.
Güven
Dilek
D
Doheny Retina Institute, Doheny Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
Weiland
James D
JD
Fujii
Gildo
G
Mech
Brian V
BV
Mahadevappa
Manjunatha
M
Greenberg
Robert
R
Roizenblatt
Roberto
R
Qiu
Guanting
G
Labree
Laurie
L
Wang
Xiaopeng
X
Hinton
David
D
Humayun
Mark S
MS
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation / Q000009:adverse effects* / Q000379:methods*; D004567:Electrodes, Implanted / Q000009:adverse effects*; D005549:Foreign-Body Reaction / Q000209:etiology / Q000473:pathology*; D008839:Microelectrodes / Q000009:adverse effects; D019736:Prostheses and Implants / Q000009:adverse effects*; D012160:Retina / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D012162:Retinal Degeneration / Q000473:pathology* / Q000503:physiopathology* / Q000534:rehabilitation / Q000601:surgery; D013997:Time Factors