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.

Science Illustrated - - HUMANS -

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.

Rhian Lewis has been blind for years, but af­ter hav­ing a chip trans­planted to her retina, she can once again tell the time.

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