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K. Nishida, M. Kamei, M. Kondo, T. Sakai, Z. Du, Y. Kitaguchi, K. Nakauchi, H. Sakaguchi, T. Fujikado, Y. Tano; Suprachoridal-Transretinal Stimulation (STS) Generates EEP in a Middle-Sized Animal Model of Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3024. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
We have developed a unique retinal prosthesis system, the suprachoridal-transretinal stimulation (STS) system. The purpose of the present study is to develop a rabbit retinal degenerative model and to evaluate the efficacy of the STS system in this model.
Verteporfin (0.47 mg/kg) was intravenously injected in pigmented rabbits (n=5, weighing 2.0-2.3 kg), and a red light emitting diode (LED) light (illuminance: 9.5 mW/cm2, transmission peak wavelength: 640 nm) was irradiated for 90 minutes. Ophthalmological examinations including fundus photograph, fluorescein angiogram (FA), and full-field and focal electroretinogram (ERG) were performed before, 1 week and 1 month after the irradiation. One month after the irradiation, we inserted an STS stimulating electrode into a scleral pocket created in the damaged area and tried to elicit an electrical evoked potential (EEP). The rabbits were then euthanized, and the eyes were enucleated and prepared for HE staining and histological evaluation.
We observed chorioretinal changes in the visual streak 1 week after the irradiation, which lasted for one month. The damaged area was as wide as a visual angle of 30° and showed hyper-fluorescence in the FA. Histologically, a marked disruption of the outer nuclear layer and the photoreceptor layer were observed in the damaged area, while the inner retina was preserved. We could not record any response in focal ERGs in the damaged area. In contrast, we were able to measure EEPs by electrically stimulating the damaged area with the STS system.
EEPs could be measured by electrical stimulation with the STS system in the area where focal ERGs could not be recorded, suggesting that the STS system may be useful for eyes with diseases in which the outer retinal layer is damaged.
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