By: Kyle Sexton BME 281, Section 2 October 2, 2012

Visual Prostheses  Used to enable the blind to see  Can help to solve the problem of blindness  Cortical Stimulation  Stimulation to visual cortex  Very limited and did not produce great results  Optic nerve implant  Retinal Stimulation 1. Epiretinal- electrodes on top of retina 2. Subretinal- electrodes implanted underneath the retina

Retinal Implants  Two types  Subretinal- does not need any outside camera  Epiretinal-Implanted on the bottom of the retina and the image is transmitted from the camera to the electrode array which stimulates the retina

Retinal Implants  The main use for retinal implants is for helping the disease called retinitis pigmentosa  The photoreceptors in the retina slowly decay in the macular layer of the retina  The disease is incurable but the nerves remain functional  The electrodes attach to the nerves and stimulate them to form a sensation of light

Cortical implant  Bypass the retina and relay images directly to brain  Useful if patients has had eye loss or trauma  Restore vision to patients with retinal degenerative diseases

Cortical implants  In late 90’s the use of intracortical microstimulation of the visual cortex was studied in a forty-year-old woman  She had been blind for 22 years  Thirty-eight microelectrodes were implanted in the right visual cortex for four months  Repeated stimulation over a period of minutes made a gradual decrease in phosphene brightness

Optic Nerve Implant - Stimulates the optic nerve - Image on the camera cause neurostimulator to send a signal to the implant of electrodes - Patients learn how to decipher the phosphenes  in order to see and recognize objects

Limitations  Lack of availability of implantable electronics  Surgery is risky and may cause damage to the brain  Different people and different diseases have different results  External power sources  vision is limited  small interval of space, limited pixels  Outlines of objects, in shades of gray

Professional and Ethical Responsibility  Surgery for the implants can be risky  People must analyze the benefits over the risks.  Providing this type of technology to patients is required by professionals  This type of treatment can help disabled people to live independently

Works Cited  Akay, Metin. Handbook of Neural Engineering. Hoboken, NJ: Wiley, Print  DiLorenzo, Daniel J., and Joseph D. Bronzino. Neuroengineering. Boca Raton: CRC, Print.  Degenaar,Patrick “Neurobionics Group Research”  "Epiretinal Implant." Epiretinal Implant. N.p., n.d. Web. 01 Oct  Greenemeier, Larry. "Scientists Set Sights on an Implantable Prosthetic for the Blind: Scientific American." Science News, Articles and Information. 19 Mar Web. 27 Feb  "Retinal Chip Implant Undergoes Clinical Trials." Retinal Chip Implant Undergoes Clinical Trials. N.p., n.d. Web. 01 Oct  "Toward Wide-Field Retinal Prosthesis." Neural Engineering (2009). Ncbi.gov. 20 May Web. 26 Feb  Weiland, James D. "Visual Prosthesis." Proceedings of the IEEE 96.7 (2008). NYTimes.com. Web. 26 Feb  Schmidt, E. M., M. J. Bak, F. T. Hambrecht, C. V. Kufta, D. K. O'Rourke, and P. Vallabhanath. "Feasibility of a Visual Prosthesis for the Blind Based on Intracortical Micro Stimulation of the Visual Cortex." Brain (1996): Print.