Bionic Vision - Seeing into the Future

[14/10/2016]

Bionic Vision - Seeing into the Future

 

 

Some of us (the Trekkies) will be familiar with Lieutenant Geordi La Forge, who is a character from the popular TV Series, Star Trek – The Next Generation. He was the Chief Engineer of the USS Enterprise and wears this ‘cool’ Visor which allows him to see because he was blind from birth. This amazing technology to restore sight may not be as far away from reality as we once thought!

Ophthalmology is a very fast moving, technologically dependent specialty of medicine and with the research and innovations currently in this field,  we are indeed living in exciting times. Bionic Eye Research has come to the fore recently after decades of developmental and exploratory work and there are currently 2 products which are available in Europe and USA.

 
 

What is Bionic Vision?

This actually refers to the development of a visual prosthesis intended to restore functional vision to people who are blind or severely visually impaired. Research work has been focused on developing implants which can be surgically placed in different locations within the eye in order to capture light (and images) and subsequently transmit the information to an external device for interpretation.

 

Argus II implant

This is the best-known retinal prosthesis and the first to be approved for use in USA and Europe. It is an epiretinal implant (placed in front of the retina) and is developed by a company called Second Sight (in USA). It consists of an external component which is a video camera mounted onto a pair of glasses and an internal component (an array of electrodes) ‘tacked’ on to the macula (the central part of the retina). (See image below) The recipient has to use head scanning movements in order to acquire visual information.

The Argus II is currently approved to treat patients with degenerative retinal diseases such as Retinitis Pigmentosa(RP) and Choroideremia and there are studies ongoing to look at using this implant in Age related Macular Degeneration as well. As to date, the Argus II implant has been implanted in 190 patients worldwide and results do indicate that the device is a reasonably reliable and stable option for patients with these degenerative retinal diseases.  

 
 

Alpha – IMS

This prosthesis is developed by Retinal Implant (Germany) and is a microchip designed to be placed under the retina at the fovea (centre of the macula). This microchip consists of light-sensitive photodiodes joined to microelectrodes and it does not require an external camera. An external power module however, is implanted under the skin (behind the ear) and coupled to the photodiodes.  (See image below)

The Alpha-IMS is approved in Europe for use in patients with RP and one advantage with this device is that head scanning is not required to locate objects and normal eye movements are good enough.

 
 
 
 

Managing Patients’ Expectations

The devices described above represent great leaps forward in terms of Bionic Eye Research but whilst this technology does make a difference to the lives of its blind recipients, the level of vision achieved by these prostheses are still rudimentary.

There are very strict criteria which have to be fulfilled before a patient is considered suitable for these devices and one of them is the expectations after implantation. Patients can expect to see shapes and shadows rather than actual details of images and they also have to be fully committed to an intensive visual rehabilitation programme. Bear in mind that the patients who have received these implants so far have been almost (if not totally) blind and going from complete darkness to seeing shapes and shadows is a big improvement.

These prostheses are implanted surgically and the surgical procedures are very complex and only highly skilled (and specifically trained) retinal surgeons are able to perform the surgery. Currently, the majority of surgeons who are implanting these have been involved with the development of these devices from the outset and not many ‘external’ retinal surgeons have had the opportunity to use them.  And of course, with any new sophisticated technology, there is a vastly significant ‘price tag’ attached to it as well.

 

What the Future holds?

There are currently approximately 20 research groups around the world actively engaged in the field of Bionic Vision and we look forward to seeing further innovations and refinements of these devices.

Recent advances in wireless technology and silicon chip design have also made the possibility of bypassing the retina altogether and having implants in the visual cortex which directly stimulate the brain!