97th DOG Annual Meeting 1999
WHICH IDEAS LEAD TO THE CONCEPTUAL DEVELOPMENT OF VISUAL CHIP-IMPLANTS?
C. E. Uhlig, S. Taneri, F. P. Bollmann, H. Gerding
First attempts to trigger off visual perceptions date back to the 18th century (LeRoy, 1755). Experiments with transcranial stimulation in those days were naturally condemned to be failures and in some cases induced significant side effects.
Only in the course of the present century the correlation between electrical stimulation and light perception was again discussed in detail. The effort of Meyer-Schwickerath and Magun in 1950 to differentiate between disorders of the peripheral or central retina by means of frequency-dependent electrical stimulation showed equally little sufficient and convincing results as the endeavours of Potts et al. in 1968 to widen the ophthalmologically usable scope of diagnostics by electrical stimulation of the bulbus with occipital electrodes.
New therapeutic considerations in the 60s and 70s to supplant lost visual functions by means of using electrodes on the retinal level were soon abandoned. The electrodes cortically applied by Brindley though were able to provoke light perception, however, and could in some cases even be perceived simultaneously. A topological attribution of cortically applied stimuli and subjective light perception was achieved, which did not, however, render any therapeutically usable results apart from some seemingly ill assorted perceptions of shapes.
The new means and methods of recent times such as chip production and technology, of micromechanics or of micro system techniques as well as the continuing progredient developments in vitreo-retinal and sub-retinal surgery have opened new prospects for the development of new vision aids or protheses. Currently there are world-wide five projects following different approaches with the aim of definitely developing and clinically applying retinal implants. Alternatively the optimization of opticus and cortex supported implants is being attempted.
Different approaches of projects are presented and exemplified and illustrated by own works with the EPI-RET.
Sponsored by the BMBF (German National Ministry of Education and Research), Cooperation within the EPI RET-Consortium (01 IN 501)
Dept. Of Ophthalmology, Univ. of Münster, Domagkstr. 15, D-48129 Münster