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Artificial Vision

Artificial Vision. By Justin Martin. Vision Loss. 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

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Artificial Vision

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  1. Artificial Vision By Justin Martin

  2. Vision Loss • 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.

  3. Prosthetic Replacements • 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.

  4. Intraocular Retinal Prosthesis • 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

  5. Clinical Trial • 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

  6. Learning Retina Implant • 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

  7. Clinical Trial • 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

  8. Future for Artificial Vision • 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

  9. References • 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 • www.boston.com/news/globe/magazine/articles/2004/12/05/the_bionic_eye/ • www.sciencecodex.com/get_ready_for_a_bionic_eye • www.revophth.com/archive/newsletter/01_06retina.htm

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