A company called Second Sight recently went bankrupt and out of business. They made of retinal implants for the blind, including those that were totally blind and had no perception between even a light and dark room. The thing is the technology was too expensive for them to support in constant experimental phase - but it worked and several hundred people have them today. Their original model had vision in 16 pixels. Not much, but enough to help navigate. The second generation was in 60 pixels. Again not amazing, but getting som e shapes and objects not. Their third generation had 250 pixels. Presumably since the technology worked and continued to improve the only hold back is cost. As technology costs come down, as almost all do in time, it's there to be used on patients. Someone is going to grab it and continue to develop it until the cost comes down enough and then blindness will disappear, at least for the well off, overnight.