There are a number of blinding disorders which are primarily due to
photoreceptor or outer retinal degeneration/destruction. These include
but are not exclusive to diseases such as retinitis pigmentosa and age
related related macular degeneration. We have tested the feasibility of
developing a retinal implant/Chip which could provide form vision to this
subset of blind patients. This visual prosthesis would be situated in the
eye cavity on the retinal surface. It would create the sensation of seeing
light by electrical stimulation of the remaining retinal cells which remain
relatively intact despite severe photoreceptor loss. Moreover, by
converting images into pixels and then electrically stimulating the retina
by a pattern of electrodes, this device would recreate at least in part the
We have conducted labaratory experiments as well as clinical tests in
blind humans. Our results show that in an otherwise totally blind eye,
controlled electrical stimulation in patterns can produce vision compatible
with limited mobility and can generate forms in the shape of large letters.
The patients also often described seeing color and direction of
movement. The details of these tests are provided in the following select
references. However, as a word of caution, these results are from
short term tests. We are currently trying to evaluate if these initial
encouraging results uphold during more prolonged tests.
If you or someone you know is blind especially from a retinal problem
such as retinitis pigmentosa and would like furhter information you can
call or write to us at the address and phone number below. Additionally,
we welcome interested students at all levels who would like to work
with us in the development of a retinal based visual prosthesis.
For further information please contact Dr. Mark Humayun, Dr. Wentai Liu, or Elliot McGucken
1) Humayun MS, de Juan E Jr., Dagnelie G, et al. Visual perception
elicited by electrical stimulation of retina in blind humans. Archives of
OPhthalmology; vol 114; pages 40-46, 1996
2) Humayun MS, Propst RH, de Juan E Jr., et al. Bipolar surface
electrical stimulation of the vertebrate retina. Archives of Ophthalmology;
vol 112; pages 110-116, 1994.
Medical Retina Discussion Board