Disease Distorts Vision
Many different eye diseases can make you blind. Lens lumps cause blurred vision, whereas burst retina blood vessels make you see dark spots.
The first thing that Rhian Lewis sees is small, sharp light flashes that resemble the night sky. But after a few weeks of practice, her brain learns to interpret the flashes, so she can see the bright contours of her surroundings. The image is black and white and blurred, but for the first time in more than five years, she can make out plates and cutlery on a laid table and see what time it is. A congenital vision defect has gradually broken down Rhian Lewis’ retina, but the 49-yearold British woman is part of a small group of blind people, who have now regained some of their vision by having a new electronic chip implanted into their retinas.
The most recent version of the chip, the Alpha AMS, was introduced in the EU in 2016 and has undergone clinical testing in Germany and the UK. The small chip functions as an electronic retina, and once it has been implanted into the eye, the blind person only needs to activate it to be able to see again. In principle, the implant consists of the same type of electronic image sensor which is included in a digital camera. The chip replaces the lightsensitive cells that have been destroyed in the blind person’s eyes and sends data about the light to the brain via the optic nerve, so an image is produced in the centre of vision.
The chip is one of several sophisticated treatments that doctors can now or very soon use on blind people. About 85 % of all cases of blindness can probably be prevented or treated with existing technology. Apart from electronic implants, scientists are also working with biological solutions. Stem cells can recreate damaged eye tissue, and virus can reprogramme the cells to function correctly again. And if everything else fails, doctors will probably one day be able to replace the entire blind eye by a normally functioning eye from a deceased donor. Cataract causes blindness A total of 314 million people are estimated to be at least partially blind, often due to disease, malnutrition, congenital gene defects, or accidents. Total blindness, by which the person cannot tell the difference between light and darkness, exists in about 39 million people or 0.5 % of the world population.
The group of blind people also includes those who, in spite of glasses or contact lenses, see more than 10 times as poorly as a person with ordinary vision. For instance, although you might otherwise have perfect vision, you are considered partially blind, if your field of vision is very narrow.