By Justin Martin

 Affects thousands of people each year  Retinitis Pigmentosa is the leading cause of inherited blindness. ◦ 1.5 million people are affected worldwide  Age-related macular degeneration ◦ Leading cause of vision loss for adults over 65 ◦ 700,000 newly diagnosed patients yearly in the United States.

 Components ◦ Image capturing device  This is usually an externally worn camera ◦ Processor  Takes the pictures and translates them into electronic signals, which are then sent to the electrode array ◦ Electrode Array  The microelectrode array is connected to the retina and stimulates any remaining photoreceptors. This is done by electrical impulses. ◦ Battery  The battery is usually externally worn and about the size of a pager.

 Developed by Dr. Humayun of the University of California  Device consists of external and internal components ◦ External Units:  External camera that is built into a pair of lightweight glasses  External worn battery ◦ Internal Unit:  A small visual processing unit that is implanted behind the patient’s ear  Microelectrode Array  Consisting of 16 platinum microelectrodes that vary in size  Held into place by a small tack that makes sure the array stays connected to the retina  The array is connected to the processor by a cable

 The product was first tested in dogs to see if there was any rejection at the implant site ◦ A 2 to 3 month period showed no inflammation or rejection  The only irritation occurred at the site of the tack  6 patients suffering from vision loss  First signals were sent to the processor through a computer to simulate light ◦ This was done to see if the impulses sent to the retinal fibers stimulated any brain activity  Then the external camera was used to send pictures to the processor  After a few months ◦ Patients were able to detect when lights were on or off ◦ Patients could describe an object’s path of motion ◦ Patients could count discrete objects  Showed that the healthier a patient’s eyes were, the lower the threshold current the electrode array needed to operate properly

 Similar to the IRP device  The microelectrode array consists of 50 electrodes instead of 16  An externally worn processor takes the information from the external camera and translates it into data which is then sent wirelessly to the microelectrode array inside the eye  The receiver on the microelectrode array has an infrared receiver that wirelessly transmits data and energy

 11 patients with retinitis pigmentosa  The patients were immediately able to distinguish between light and dark and recognize the outlines of objects  After a few month of use with the device ◦ Patients could read letters and form them into words ◦ Patients could recognize different objects, like distinguish between a knife, fork and spoon ◦ The most remarkable thing is the patients could tell differences in height and distinguish arm movement of people from 20ft away  After the trials were concluded, the devices were removed, but one patients was so pleased with the device he kept it in and has been using it for years

 Change the external glasses mounted camera into a contact lens with a camera incorporated.  Changing the wired array to a wireless array, this will eliminate the need to have wires implanted into the patients skull.  Incorporate solar cells into the chip to convert the light entering the eye into energy, this would eliminate the need for externally worn batteries  When the technologies becomes available, scientists hope to have arrays consisting of thousands of microelectrodes, this would increase the resolution of images people could see

 Javaheri, Michael, David S. Hahn, Rohit R. Lakhanpal, and Mark S. Humayun. "Retinal Prostheses for the Blind." Annals Academy of Medicine 35.3 (2006). Web  cles/2004/12/05/the_bionic_eye/  ic_eye  6retina.htm