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Yukari Nakano, Yasuo Terasawa, Hiroyuki Kanda, Koji Osawa, Motoki Ozawa, Tomomitsu Miyoshi, Hajime Sawai; Effect of stimulus pulse on evoked potential amplitude in the superior colliculus of rats by electrical stimulation with Suprachoroidal-Transretinal Stimulation (STS) retinal prosthesis. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3715.
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© ARVO (1962-2015); The Authors (2016-present)
Electrical stimulation with rectangular waveform is generally used for retinal prosthesis irrespective of the place of electrode implantation, but to find out more effective electrical stimulation parameter is one of the important elements for the development of retinal prosthesis.In order to find out more effective electrical stimulation parameter, in this study, we examined the effect of waveforms on evoked potential by electrical stimulation with Suprachoroidal-Transretinal Stimulation (STS).
Platinum stimulation electrode (D: 0.5 mm, H: 0.3 mm) was set onto the region of partial scleral resection the eyeball of normal rats (Long-Evans, N=10) and retinal degenerated rats (Royal College of Surgeons; RCS, N=10) under anesthesia.Current pulses (inward current-first) were applied between the stimulation electrode and the return electrode (platiniridium wire, D: 0.2 mm) that was placed inside the eye.Three types of waveforms (rectangular, triangular and sinusoidal wave) were used as current pulse.The pulse duration of the three waveforms was fixed at 0.5 ms in order for them to have the same quantity of electric charge by adjusting the amplitude of electric current.Evoked potential by electrical stimulation was recorded with a needle electrode (tungsten: 0.5 MΩ) in the superior colliculus.
Distinct responses were observed at approximately 5.0 ms (P1) and 10 ms (N1) after stimulation in all the rats irrespective of waveforms.In both normal and RCS rats, evoked potential amplitude had significant differences between rectangular and triangular, rectangular and sinusoidal wave (p<0.01, paired t-test).Rectangular wave elicited the lowest response.The evoked potential amplitudes of triangular and sinusoidal wave were an average of 1.5 and 1.9 times, respectively, as high as that of rectangular wave.
Sinusoidal wave output was the highest in both normal and RCS rats among rectangular, triangular and sinusoidal wave, and rectangular wave output was the lowest (Fig.1).This result corresponded to previous studies in vitro [Goo, Yong Sook et. al., TJSMBE Vol. 51, 2013].This suggested that electrical stimulation could be applied with a smaller quantity of electric charge by using sinusoidal wave output.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Fig1. Evoked potential peak-to-peak amplitudes. RCS (N=10). Error bars: SD.
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