Publications
1. Rizzo, J.F., J.L. Wyatt, J. Loewenstein, S. Kelly and D. Shire,
“Accuracy and Reproducibility of Percepts Elicited by Electrical Stimulation of the Retinas of Blind and Normal Subjects,” ARVO Lecture Abstract, Investigative Ophthalmology and Visual Science, vol. 42, no. 4, May 2001, p. s942.2. Caulfield, R.E., J.L. Wyatt Jr., and J.F. Rizzo, “Calculated Power Limits Affecting Retinal Prosthesis Design,”
ARVO Poster Session Abstract, Investigative Ophthalmology and Visual Science, vol. 42, no. 4, May 2001, p. s814.3. Shire, D.B., J.L. Wyatt and J.F. Rizzo, “Progress Toward an Inflatable Neural Prosthesis,” ARVO Poster Session Abstract, Investigative Ophthalmology and Visual Science, vol. 42, no. 4, May 2001, p. s812.4. Rizzo, J.F., J. Wyatt, M. Humayun, E. DeJuan, W. Liu, A. Chow, R. Eckmiller, E. Zrenner, T. Yagi, G. Abrams, “Retinal Prosthesis: An Encouraging First Decade with Major Challenges Ahead,” Editorial, Ophthalmology, vol. 108, no. 1, January 2001.5. Grumet, A.E., J.L. Wyatt, Jr., J.F. Rizzo, “Multi-electrode stimulation and recording in the isolated retina,”
Journal of Neuroscience Methods, 101, pp. 31-42, 2000.6. Loewenstein, J., J.F. Rizzo, J. Wyatt and S. Kelly, “Acute Intraocular Electrical Stimulation of the Human Retina,” XIV Int’l. Congress of Eye Research, Oct, 2000, Santa Fe, NM.7. Shahin, M.E., J.F. Rizzo, J. Wyatt, J. Loewenstein, “Evaluation of External Electrical Stimulation of the Eye as a Screening Test for Acute Intraocular Retinal Stimulation Studies,” ARVO Poster Session Abstract, Investigative Ophthalmology and Visual Science, vol. 41, no. 4, April-May 2000, p. s860.8. Rizzo, J.F., J. Wyatt, J. Loewenstein, S. Kelly, “Acute Intraocular Retinal Stimulation in Normal and Blind Humans,” ARVO Lecture Abstract, Investigative Ophthalmology and Visual Science, vol. 41, no. 4, April-May 2000, p. s102.9. Grumet, A.E., J.F. Rizzo, J. Wyatt,
“In-Vitro Electrical Stimulation of Human Retinal Ganglion Cell Axons,”
ARVO Poster Session Abstract, Investigative Ophthalmology and Visual Science, vol. 41, no. 4, April-May 2000, p. s10.10. Rizzo, J.F., J. Loewenstein, S. Kelly, D. Shire, T. Herndon and J.L. Wyatt, “Electrical Stimulation of Human Retina with a Micro-Fabricated Electrode Array,” The Association for Research in Vision and Ophthalmology Annual Meeting (ARVO), Ft. Lauderdale, FL, p. S783, May 1999.11. Moss, J.D., M.M. Socha, J.L. Wyatt and J.F. Rizzo, “Hermetic Encapsulation Testing for a Retinal Prosthesis,” The Association for Research in Vision and Ophthalmology Annual Meeting (ARVO), Ft. Lauderdale, FL, p. S732, May 1999.12. Socha, M.M., J.D. Moss, M. Shahin, T. Herndon, J.L. Wyatt and J.F. Rizzo,
“Mechanical Design and Surgical Implantation of Second Generation Retinal Prosthesis,” The Association for Research in Vision and Ophthalmology Annual Meeting (ARVO), Ft. Lauderdale, FL, p. S735, May 1999.13. Grumet, A.E., J.F. Rizzo and J.L. Wyatt, “Ten Micron Diameter Electrodes Directly Stimulate Rabbit Retinal Ganglion Cell Axons,” The Association for Research in Vision and Ophthalmology Annual Meeting (ARVO), Ft. Lauderdale, FL, p. 734, May 1999.14. Rizzo, J.F., J. Loewenstein and J. Wyatt “Development of an Epiretinal Electronic Visual Prosthesis: The Harvard-Medical Massachusetts Institute of Technology Research Program,” Retinal Degenerative Disease and Experimental Theory, pp. 463-47, Kluwer Academic/Plenum Publishers, 1999.15. Rizzo, J.F. and J.L. Wyatt,
“Retinal Prosthesis,” Age-Related Macular Degeneration, J. Berger, S.L. Fine, M.G. Maguire, eds., Mosby Publishers, 1999, pp. 413–432.16. Grumet, A.E., J.L. Wyatt, and J.F. Rizzo, “Multi-Electrode Recording and Stimulation of the Salamander Retina In Vitro,” The Association for Research in Vision and Ophthalmology Annual Meeting (ARVO), Ft. Lauderdale, FL, May 1998.17. Rizzo, J.F. and J. Wyatt, “Prospects for a Visual Prosthesis,”
The Neuroscientist, vol. 3, no. 4, pp. 251–262, 1997.18. Wyatt, J. and J. Rizzo, “Ocular implants for the blind,” IEEE Spectrum, pp. 47–53, May 1996.
Report
The Retinal Implant Project, a collaboration between the Massachusetts Institute of Technology and the Massachusetts Eye and Ear Infirmary, involves the design of a microelectronic prosthesis to help restore some functional vision to patients with retinal diseases such as retinitis pigmentosa and macular degeneration. These patients lose vision as a result of degeneration of the photoreceptor cell layer in the retina. The implant chip will sit against the retina and receive power and visual signal information from a wireless driver outside the eye. It will electrically stimulate the healthy ganglion cells on the front surface of the retina, which send visual information to the brain. The concept is similar in principal to the cochlear implant for the deaf.
One focus of the project has been retinal stimulation trials on humans. In these trials, a retinal surgeon temporarily inserts a flexible microfabricated electrode array into the eye and against the retina. The other end of this device remains outside the eye, connected to stimulation circuitry. The patient describes what he or she sees when current is passed through the electrodes. After a few hours of stimulation, the electrode array is removed from the eye. These trials have generated phosphene perception, and some very crude form percepts. MIT graduate student Shawn Kelly designed, built and tested the battery-powered stimulator, put it through hospital approval proceedures, and operates it during surgery as part of the experimental team. This work was funded in part by Catalyst.
Mr. Kelly’s doctoral project is to create an efficient power system for an implantable chip. In his RF-driven design, a primary coil outside the eye generates a magnetic field, which is received by a secondary coil implanted in the eye. The resulting AC voltage passes through an active rectifier, which is more efficient than a standard diode. The electrodes are stimulated in an efficient manner, and capacitively stored charge is recovered from stimulated electrodes to stimulate other electrodes. This system will allow efficient power delivery to the electrodes, reducing excess heat generation in the eye, and allowing more electrodes to be used. All the power-saving features in Mr. Kelly’s design would be beneficial in other implantable stimulation systems, such as cardiac pacemakers and cochlear implants. We are grateful to Catalyst for funding this doctoral project in its entirety.