K.Dinakar 09A91A nd B.Tech, ECE. P.S.V.S.Jagdish Babu 09A91A nd B.Tech, ECE.

CONTENTS  Introduction  How are we able to see?  How is vision impaired?  Corneal transplants  What are bionic eyes?  The surgery!  Some facts about bionic eyes  The analogy  Advantages of bionic eyes  Conclusion

INTRODUCTION  There is no replacement for human sight. It is simply incomparable because of its capacity to see. Our life is full of pictures as we daily see.  If scientists give birth to ideas, then it is we engineers who put life into those ideas. We certainly know the magic route to reach our goal: Science and Technology.  Today, we talk of artificial intelligence that has created waves of interest in the field of robotics. When this has been possible, why not artificial vision?  It is important to know few facts about the organ of sight i.e., the Eye before we proceed towards the technicalities involved.

HOW ARE WE ABLE TO SEE?  For vision to occur, 2 conditions need to be met : 1. An image must be formed on the retina 2. Resulting nerve impulses must be conducted to the visual areas of the cerebral cortex for interpretation.  Four processes focus light rays, so that they form a clear image on the retina 1. Refraction of light rays 2. Accommodation of the lens 3. Constriction of the pupil 4. Convergence of the eyes

HOW IS VISION IMPAIRED?  Damage or degeneration of the optic nerve, the brain, or any part of the visual pathway between them, can impair vision.  Damage to the visual pathway does not always result in total loss of sight. Depending on where damage occurs, only a part of the visual field may be affected  A stroke can cause vision impairment when the resulting tissue damage occurs in one of the regions of the brain that process visual information.  A more common treatment for curing blindness has been corneal transplantation.

CORNEAL TRANSPLANTS  Surgical removal of opaque corneas and replacement with donor transplants is a common medical practice. Corneal tissue is a vascular; that is, the cornea is free of blood vessels.  Antibodies carried in the blood have no way to reach the transplanted tissue, and therefore long-term success following implant surgery is excellent.

WHAT ARE BIONIC EYES?  An artificial eye provokes visual sensations in the brain by directly stimulating different parts of the optic nerve. There are also other experimental implants that can stimulate the ganglia cells on the retina or the visual cortex of the brain itself. There is more concentration given to the production of artificial retinas.  Many types of artificial eyes have been designed and research is still going on. There is no standard model in this case. Researchers are working out different types of concepts.

WORKING OF BIONIC EYES  The prototype devices are 2 millimetres across and contain some 3,500 micro photodiodes. Placed behind the retina, this collection of miniature solar cells is designed to convert natural light to electrical signals.  A Belgian device has a coil that wraps around the optic nerve, with only four points of electrical contact. By shifting the phase and varying the strength of the signals, the coil can stimulate different parts of the optic nerve.  Implants of a microchip, smaller than the head of a pin and about half the thickness of a sheet of paper were used to remove blindness.

THE SURGERY!  The microsurgery starts with three incisions smaller than the diameter of a needle in the white part of the eye. Through the incisions, surgeons introduce a vacuuming device that removes the gel in the middle of the eye and replaces it with saline solution.  Surgeons then make a pinpoint opening in the retina to inject fluid in order to lift a portion of the retina from the back of the eye, creating a pocket to accommodate the chip.  The retina is resealed over the chip, and doctors inject air into the middle of the eye to force the retina back over the device and close the incisions.

THE SURGERY!

SOME FACTS ABOUT BIONIC EYES  Scientists at the Space Vacuum Epitaxy Centre (SVEC) based at the University of Houston, Texas, are using a new material, comprising tiny ceramic photocells that could detect incoming light and repair malfunctioning human eyes.  The artificial retinas constructed at SVEC consist of 1,00,000 tiny ceramic detectors, each 1/20th the size of a human hair.  The assemblage is so small that surgeons can’t safely handle it. So, the arrays are attached to a polymer film one millimetre in size. After insertion into an eyeball, the polymer film will simply dissolve leaving only the array behind after a couple of weeks.

THE ANALOGY  There is a great degree of coherence between the ways our eyes function to that of a change over time as the respective camera. Perhaps – our eyes had been the technologies are further developed and inspiration behind the camera’s invention.  From the structural point of view the eye may be compared with a camera. The eyelids act as a shutter and there is an entrance – the cornea; a diaphragm to regulate aperture and therefore the amount of light entering – the iris; a lens to focus the image

ADVANTAGES OF BIONIC EYES  Discretion between night and day so that the body clock may be synchronized to the 24-hour day.  Detection of movement and obstacles to aid mobility.

CONCLUSION  Restoration of sight for the blind is no more a dream.  Bionic Eyes have made this true. Though there are a number of challenges to be faced before technology reach the common man, the path has been laid.  It is just a matter of 2-3 years that the blind will be able to see through these Bionic Eyes; thanks to Science and Technology.

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