how many hospitals have adopted this technique?
and what is the level of this in the market?

A visual prosthesis, often called a bionic eye, is an experimental visual device intended to restore functional vision in those who suffer from partial or total blindness. In 1983, João Lobo Antunes, Portuguese physician, implanted a bionic eye in a person blind from birth. Many devices have been developed, usually modeled in the cochlear implant or bionic hearing devices, a type of neural prosthesis in use since the mid-eighties. The idea of using electric current (for example, electrically stimulating the retina or the visual cortex) to provide sight dates back to the eighteenth century, discussed by Benjamin Franklin, Tiberius Cavallo and Charles LeRoy.

This bionic eye system will consist of a small digital camera, external processor and an implant with a microchip and stimulating electrodes placed surgically in the back of the eye. Learn more about how the bionic eye works.

  
A schematic diagram of a bionic eye 
placed inside the eyeball.This version 
is made of diamond, so it is completely inert.

Working

The bionic vision system consists of a camera, attached to a pair of glasses, which transmits high frequency radio signals to a microchip implanted in the eye. The electrodes on the implanted chip convert these signals into electrical impulses to stimulate the cells of the retina that connect to the optic nerve. These impulses are transmitted along the optic nerve to the centers of vision processing of the brain, where they are interpreted as an image. To benefit from this technology, patients need to have a functional visual pathway from the retina to the brain along the optic nerve, as well as some intact retinal cells. As such, the two medical conditions that this technology aims to address are retinitis pigmentosa and age-related macular degeneration.