Physiological testing of function of retinal implants with animal models

Retinal implants can - by electrical stimulation - create visual impression s in people with certain kinds of degenerative retinal diseases (e.g. Retin itis Pigmentosa). Electrically evoked potentials in the retina must be tran sferred into the visual cortex in an orderly manner, a prerequisite for any kind of form-and movement-perception. In the current developmental stage t he difficult investigations are performed in various animal models: isolate d retinae of intact chicken and of RCS-rats (a model for Retinitis Pigmento sa),as well as in anesthetised rabbits, pigs and cats with intact retinae. Our investigations show that spatially selective ganglion-cell responses ca n be recorded following focal electrical stimulation, in healthy and as wel l in degenerated retinae. Registration of activities in area 17 of the visu al cortex demonstrate that electrical retinal stimulation can indeed activa te it.