BATCH C2 Vibhor jain Mainak chakraborty Rohan seth ARTIFICIAL EYE BATCH C2 Vibhor jain Mainak chakraborty Rohan seth

BIOLOGICAL CONSIDERATIONS The ability to give sight to a blind person via a bionic eye depends on the circumstances surrounding the loss of sight. For retinal prostheses, which are the most prevalent visual prosthetic under development (due to ease of access to the retina among other considerations), vision loss due to degeneration of photoreceptors (retinitis pigmentosa, choroideremia, geographic atrophy macular degeneration) is the best candidate for treatment

GEOGRAPHIC ATROPHY MACULAR DEGENERATION

Present technologies available Argus Retinal Prosthesis Microsystem-based Visual Prosthesis (MIVIP) Implantable Miniature Telescope Tübingen MPDA Project Artificial Silicon Retina (ASR) Optoelectronic Retinal Prosthesis Virtual Retinal Display (VRD) Harvard/MIT Retinal Implant Intracortical Visual Prosthesis

ARGUS RETINAL PROSTHESIS Drs. Mark Humayun and Eugene DeJuan at the Doheny Eye Institute (USC) were the original inventors of the active epi-retinal prosthesis [ In the late 1990s the company Second Sight was formed to develop a chronically implantable retinal prosthesis Their first generation implant had 16 electrodes and was implanted in 6 subjects between 2002 and 2004

ARGUS RETINAL PROSTHESIS Five of these subjects still use the device in their homes today More recently, the company announced that it has received FDA approval to begin a trial of its second generation, 60 electrode implant, in the US Three major US government funding agencies (National Eye Institute, Department of Energy, and National Science Foundation) have supported the work at Second Sight and USC.

PARTS OF THE ARGUS RETINAL PROSTHESIS A digital camera that's built into a pair of glasses. It captures images in real time and sends images to a microchip. A video-processing microchip that's built into a handheld unit. It processes images into electrical pulses representing patterns of light and dark and sends the pulses to a radio transmitter in the glasses. A radio transmitter that wirelessly transmits pulses to a receiver implanted above the ear or under the eye A radio receiver that sends pulses to the retinal implant by a hair-thin implanted wire A retinal implant with an array of 60 electrodes on a chip measuring 1 mm by 1 mm

DRAWBACKS It provides a black and white image. Facial recognition is not possible in this case. The design is not that compact as it requires a handheld video processing unit and separate radio transmitter and radio receiver. The implantation of chip can lead to scarring of tissues. Developed optical nerve prior to blindness

OTHER TECHNOLOGIES AVAILABLE

MICROSYSTEM-BASED VISUAL PROSTHESIS (MIVIP) Designed by Claude Veraart at the University of Louvain, this is a spiral cuff electrode around the optic nerve at the back of the eye. It is connected to a stimulator implanted in a small depression in the skull. The stimulator receives signals from an externally-worn camera, which are translated into electrical signals that stimulate the optic nerve directly

IMPLANTABLE MINIATURE TELESCOPE Although not truly an active prosthesis, an Implantable Miniature Telescope is one type of visual implant that has met with some success in the treatment of end-stage age-related macular degeneration. This type of device is implanted in the eye's posterior chamber and works by increasing (by about three times) the size of the image projected onto the retina in order to overcome a centrally-located scotoma or blind spot.

TÜBINGEN MPDA PROJECT A Southern German team led by the University Eye Hospital in Tübingen, was formed in 1995 by Eberhart Zrenner to develop a subretinal prosthesis. The chip is located behind the retina and utilizes microphotodiode arrays (MPDA) which collect incident light and transform it into electrical current stimulating the retinal ganglion cells. As natural photoreceptors are far more efficient than photodiodes, visible light is not powerful enough to stimulate the MPDA. Therefore, an external power supply is used to enhance the stimulation current.

HARVARD/MIT RETINAL IMPLANT Joseph Rizzo and John Wyatt at the Massachusetts Eye and Ear Infirmary and MIT began researching the feasibility of a retinal prosthesis in 1989, and performed a number of proof-of-concept epiretinal stimulation trials on blind volunteers between 1998 and 2000. They have since developed a subretinal stimulator that sits on the outside of the eye and receives image signals beamed from a camera mounted on a pair of glasses. The stimulator chip decodes the picture information beamed from the camera and stimulates retinal ganglion cells accordingly.

Artificial Silicon Retina (ASR) Artificial Silicon Retina™ microchip (ASR™) was invented by Dr. Alan Chow and his brother Vincent Chow The ASR was designed to stimulate damaged retinal cells from within the retina to allow the cells to recreate visual signals that are processed and sent to the brain. The ASR microchip is a silicon chip 2 mm in diameter, 25 microns in thickness contains approximately 5,000 microscopic solar cells called “microphotodiodes,” these microphotodiodes convert light energy into electrochemical impulses that stimulate the remaining retinal cells which are sent via the optic nerve to the brain.

Optoelectronic Retinal Prosthesis patients suffering from degenerative retinal diseases such as Retinitis Pigmentosa and Age-Related Macular Degeneration includes a subretinal photodiode array and an infrared image projection system mounted on video goggles.

Intracortical Visual Prosthesis uses Intracortical Iridium Oxide (AIROF) electrodes arrays. These arrays will be implanted on the occipital lobe. This system will capture the image in real time, process it and then deliver the corresponding signals to an implanted chip which in turn will stimulate the intracortically implanted electrodes.

Virtual Retinal Display VRD is a display technology that draws a raster display directly onto the retina of the eye. Invented at the HIT Lab in 1991. VRD system can also show an image in each eye with a very little angle difference for simulating three-dimensional scenes with high fidelity spectral colors. Medical utilities :A system used by doctors for complex operations as surgeons can keep track of vital patient data, such as blood pressure or heart rate, on a VRD. Military utilities: VRDs were initially developed for military use. The commander of a armored vehicle can view its VRD. This allows him to choose the best path and share tactical information at the same time. A similar device is used by fighter and helicopters pilots.

FUTURE PROSPECTS Implantation of the camera in the intraoccular space for sufficient control of eye movements One of the major hurdle is to obtain colour vision which is not possible yet with the available technologies using complete artificial retina.

BIONIC CONTACT LENSES The bionic contact lens is being developed to provide a virtual display that could have a variety of uses from assisting the visually impaired to the video game industry.The device will have the form of a conventional contact lens with added bionics technology. The lens will eventually have functional electronic circuits and infrared lights to create a virtual display.

Adding displays directly onto the lenses, visible to the wearers but no one else, could project critical information onto windshields for drivers or pilots or superimpose computer images onto real-world objects for training exercises