Blindness is the most severe form of visual impairment, which deprives people of the ability to see or move about unaided. It effectively robs people of the comfort and satisfaction that come with performing daily chores, even with the aid of glasses or contact lenses. However, scientists have developed a technology called bionic eye, which goal is to restore the sense of vision to people living with blindness, especially those with an eye condition known as retinitis pigmentosa and age-related macular degeneration. RALIAT AHMED writes.

The world's population is estimated to be 7 billion. Out of this number, about 285 million people are said to be visually-impaired - i.e not completely blind but can't quite see properly without some form of aid, while about 4 million are outrightly blind.

India is said to have the highest number of the blind, being home to the world's largest number of blind people. Of the 37 million people across the globe who are blind, over 15 million are from India, followed by the China.

Coming closer to home, there is said to be about 2.2 million Africans (about 1.2% of the population) who are blind. In a continent where the ratio of ophthalmologists to the population is said to be 1000000 to 1, the percentage may not be significant but it translates into huge numbers and a source of concern.

In Nigeria, there is a high prevalence of blindness in those aged 40 and above, while worldwide, the commonest causes of blindness are cataract and glaucoma.

While some of the cases may be reversible if detected early, so many more are not and can only be managed or partially alleviated. Any technique, process or aid developed to aid the partially blind is therefore very exciting and noteworthy, even if commercial.

The treatment known as bionic eye was recently developed in the US. This apparatus allows the blind to see is made up of a pair of sunglasses with a tiny video camera mounted in the bridge just above the nose. The camera captures an image and sends it down a wire to a Visual Processing Unit(VPU) hanging on the patient's belt.

The VPU which is a little larger than a smart phone converts the world's complexities into a 60-pixel image in black and white, which it sends back to transponders on the glasses. From there the image goes wirelessly to antennas wrapped around the sides of the eyeballs, and from there to the 60-electrode arrays that are tacked to the delicate retinas.

The technology which uses the Argus II Retinal Prosthesis System can provide sight by helping in the detection of light for people who have gone blind from degenerative eye diseases like macular degeneration and retinitis pigmentosa.

Medical research reveals that ten per cent of people over the age of 55 suffer from various stages of macular degeneration while retinitis pigmentosa is an inherited disease that affects about 1.5 million people around the globe. Both diseases damage the eyes' photoreceptors, the cells at the back of the retina that perceive light patterns and pass them on to the brain in the form of nerve impulses, where the impulse patterns are then interpreted as images. What the Argus II system does is to take the place of these photoreceptors.

The bionic eye system and how it works

The system runs on a battery pack that's housed with the video processing unit. When the camera captures an image for instance, a tree, the image is in the form of light and dark pixels. This image is sent to the video processor, which converts the tree-shaped pattern of pixels into a series of electrical pulses that represent 'light' and 'dark'.

The processor sends these pulses to a radio transmitter on the glasses, which then transmits the pulses in radio form to a receiver implanted underneath the wearer's skin. The receiver is directly connected through a wire to the electrode array implanted at the back of the eye, and it sends the pulses down the wire.

When the pulses reach the retinal implant, they excite the electrode array. The array acts as the artificial equivalent of the retina's photoreceptors. The electrodes are stimulated in accordance with the encoded pattern of light and dark that represents the tree, as the retina's photoreceptors would be if they were working under normal circumstance in a person with normal sight. The electrical signals generated by the stimulated electrodes then travel as neural signals to the visual center of the brain by way of the normal pathways used by healthy eyes -- the optic nerves.

It should be noted that in macular degeneration and retinitis pigmentosa, the optical neural pathways are not damaged. The brain, in turn, interprets these signals as a tree and tells the sufferer what he is seeing.

According to the trials carried out at the University of California in Los Angeles, doctors implanted the retinal chip in six patients, all of whom regained some degree of sight.

They were able to perceive shapes (such as the shaded outline of a tree) and detect movement to varying degrees. The estimated cost of this treatment is $30,000 (about N4.5 million).

This technology targets patients with retinitis pigmentosa and age-related macular degeneration but with time and more research, it is possible that in future this technology can also help patients with other vision impairment conditions.