- How human eye works?- Diseases related to eye
- What is Artificial Silicon Retina?- Implantation - Working - What is Bionic Eye?- Components- Working
- Results & Advantages- Limitations & Drawbacks
Working of human eye :
-The eye is one of the most important organs of the body.Before we learn about ASR,it is important to know the working of natural retina.
-The light coming from an object enters the eye through cornea and pupil and forms inverted image on the retina.
-The light sensitive cells of the retina gets activated with the incidence of light and generate electric signals. These electric signals are sent to the brain by the optic nerves and the brain interprets the electrical signals in such away that we see an image .-There are mainly two kinds of diseases related to eye:
Age related macular degeneration(AMD or ARMD): Macular degeneration, often age-relatedmacular degeneration, is a medical condition that usually affects older adults and results in a loss of vision in the center of the visual field (themacula) because of damage to the retina.
Retinitis Pigmentosa: It is a chronic hereditary eye disease characterized by black pigmentation, gradual degeneration of the retina and causes narrowing of vision.
What is ASR ?
Avisual prosthesis, is an experimental visual device intended to restore functional vision in those suffering from partial or totalblindness.
-In 1983 Joao Lobo Antunes, a world renowned Portuguese doctor, implanted a bionic eye in a person born blind.
- The brothers Alan Chow and Vincent Chow have developed a microchip containing 3500 photo diodes, which detect light and convert it into electrical impulses called ASR.
Size of an ASR:
- The ASR is an extremely tiny device.It has a diameter of just 2mm and is thinner than human hair.
- Surgeons make three tiny incisions no larger than the diameter of a needle in the white part of the eye.Through these incisions,they introduce a miniature cutting and vaccuuming device that removes gel in the middle of eye and replaces it with saline.
- Then,a pinpoint opening is made in the retina through which they inject fluid to lift up the portion of retina from the back of eye,which creates a small packet in the sub retinal space for the device to fit in.Finallythe retina is then released over the ASR.
Working of ASR :
- The ASR microchip is a 2mm in diameter silicon chip (same concept as computer chips) containing ~5,000 microscopic solar cells called "microphotodiodes" that each have their own stimulating electrode.
- It detects light and convert it into electrical impulses, which stimulate healthyretinal ganglion cells and these pulses are sent brain by optic nerve.
Power needed for ASR :
-For any microchip to work it needs power, and the amazing thing about the ASR is that it receives all of its needed power from the light entering the eye.
-This means that with the ASR implant in place behind the retina, it receives all of the light entering the eye. This solar energy eliminates the need for any wires, batteries or other secondary devices to supply power.
Images Shows which type of images are seen to a blind person using ASR Technology :
BIONIC EYEHistory of BIONIC EYE :
- Dr.Mark Humayun, Dr. Eugene Dejuan along with few more scientists demonstrated that a visually impaired person could be made to see light by stimulating the optic nerves behind the retina with electrical impulses.This test proved that the nerves behind retina still functioned even when the retina had degenerated. - Based on this scientists set out to create a devise that could translate images to electrical pulses that could restore vision.
- Groups of researchers have found that blind people can see spots of light when electrical currents stimulate cells,following the experimental insertion of an electrode device near to the retina.
- The main target of the research was: _small enough to be implanted in the eye. _supplied with a continuous source of power. _bio-compatible with eye tissues and its surroundings.
Components required for BIONIC EYE:
Camera mounted on eye glases:
-This camera is placed on the goggles.The camera captures the image and converts it into pixels of black and white.- The battery required for this is provided from the video processing unit.
Video processing unit (VPU) :
- Video Processing Unit is device which simplifies the image as spots of light and then reduces the image to the number of photodiodes.This is connected to goggles through conneccting wires.
Eye implant :
- These are the MICROELECTRODES array.
- 68 flat platinum electrodes of 1mm diameter are pierced through the holes into the nucleus of neurons of the occipital lobe.
Working of BIONIC EYE :
-The camera mounted on a pair of eyeglasses, captures the scene in front of the wearer and sends it to VPU on the patient's belt.
-The processor translates the image into a series of signals that the brain can understand. The group of wires pass the processed image which are generated by the processor to the transmitter.
-RF trasmitter sends the signal to the RF receiver which is near the eye implant wirelessly.
- Receiver attains the transmitted signal and demodulation is done which is sent to the microelectrode strip.
- These electrodes converts it into electrical pulses and provide it to the optic nerve.
Role of BIONIC EYE in tracking objects :
- It provides information about the edges of images rather than a whole picture. Edge information is usually sufficient for detecting and tracking objects. - The top image shows the raw output of the retina chip.
- The middle one is a picture processed from it.
- The third one shows how moving face would appear.
Results and Advantages :
- Identify the location or movement of objects and people.Recognize large letters, words or sentences.
- Helps in other activities of daily life, such as detecting street curbs and walking on a sidewalk without stepping off.
- Ability to perform visual tasks demonstrated in many patients.
- Upgradable external hardware and software to benefit from future innovations.
- The brain has an amazing ability to adapt to new input and to improve his or her understanding of what is being seen via an artificial vision system.
Limitations and Drawbacks :
- Repairing is difficult if any of the devices got damaged.
- Those who lost their visions due to other reasons could not use this device.
- It may not work for people blinded as children or as infants, because the visual cortex do not develop normally.
- Surgery is required to implant the electrode array.The approximated cost of the device is $70,000.Conclusion :
- Revolutionary piece of technology.
- The first useful artificial eye is now helping a blind man walk safely around and read large letters.
- Good news for AMD and Retinitis Pigmentosa patients.
-Research is going for high resolution images.
THANK YOU !!References :