Electrical Stimulation of Isolated Rabbit Retina

Several research groups in the world are trying to restore useful vision for the patients of degenerate retina, such as retinitis pigmentosa (RP) and age related macular degeneration (ARMD) with retinal prosthesis. Recently Korean consortium launched for developing retinal prosthesis and as part of Korean retinal prosthesis project we provide preliminary experimental results regarding voltage parameters for the stimulation of isolated retina. Voltage stimulus was delivered via one of the channel of microelectrode array (MEA) and ganglion cell activities were recorded with remained 59 channels. We changed the voltage amplitude from 0.5 V to 3 V, which showed that threshold level for reliable ganglion cell response was 1.5 V. The calculated threshold for charge densities was 2123 muC/cm2 and charge delivery was 15 nC/phase. When we changed the stimulus duration from 100 mus to 1200 mus with fixed voltage of 2 V, the threshold level was 300 mus. The calculated charge densities and charge delivery were 1698 muC/cm2 and 12 nC/phase, respectively. Even after the block of on-bipolar cell with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities.