Micro-implants acting as sensors and signal transductors are also proven to be a valid therapeutic tool for hearing loss and are now trialled to re-establish vision in some forms of blindness.
The cochlear implant or bionic ear provides a sense of sound to those who are profoundly deaf or severely hard of hearing. They are implanted into the auditory brain-stem and the ideal candidates are adults or children who have relatively recently lost their hearing or have extremely limited hearing. For congenital deafness however, there is a window of opportunity between 1,5 and 2 years of age if an implant is to result in the development of normal speech.
A visual prosthesis, often referred to as the bionic eye is still experimental, with some devices modelled on the cochlear implant. One option is to implant electrodes in place of the photoreceptors in the back of the eye, and send a camera reading from the electrodes to the visual cortex. Another, more invasive option is to bypass the retina altogether and send a reading from a camera directly into the visual cortex. Bionic contact lenses are also being developed with electronic circuits and infrared lights to create a virtual superimposed display that could have a variety of uses from convenience applications (e.g. accessing a city map) to assisting the visually impaired to playing video games.