Seeing the light

Imagine being in your early thirties, married and excited about what life has in store for you.  One day, you start to notice that your peripheral vision is not as good as it once was.  You have a hard time detecting things that are not right in front of you; objects and people start to appear very blurry; reading and driving become impossible.  After consulting your doctor about this problem, you are told that you have a genetic condition called retinitis pigmentosa.  There is nothing that can be done, and eventually you will lose your sight completely.  You will just have to adjust to this new way of life.

In the eye, the cells that convert light signals from the external world into neural signals are called photoreceptors (the rod and cone cells in the diagram below).  They sit at the back of the eye and detect light as it hits the retina.  Once they detect this light, they have to translate it into a language the brain can understand, crucial for transmitting visual information to the brain.  Retinitis pigmentosa causes degeneration of these rod and cone cells, and therefore leads to the breakdown of the interface between the world (light) and the brain.  Without these cells, information about a visual scene becomes stuck and unable to get through to the brain to be processed; the brain cannot interpret visual information, eventually leading to blindness.

picture of the retina

(Jamie Simon, Salk Institute for Biological Studies)

 Larry Hester was diagnosed with retinitis pigmentosa more than 30 years ago, but recently, he was able to see light again for the first time in many years.  Researchers at Duke University implanted a device with many tiny electrodes that could essentially bypass the damaged rods and cones to send information to the brain.  Here is how it works: Larry wears glasses with a video camera attached, which sends a signal about what Larry is looking at through a tiny wire to a computer attached to his belt.  The computer receives the information and relays it to the electrodes on the retina, which activates the cells that project into the brain.  The device is translating the light information into neural activity, giving Larry the ability to experience and interpret the image he is looking at.  At a basic level, the device is able to perform the function of the photoreceptors that have died.

See Larry’s amazing experience here:

It is important to note that this technology is new and limited, giving Larry only a blurry version of the world.  Despite this, I have no doubt that the technology and its use will continue to improve rapidly, inching closer and closer to giving people normal vision.  Larry says it is his dream to be able to see his wife’s blue eyes again.  Although he is not able to achieve this with his current implant, at least he is one step closer.

Dr. Paul Hahn, an Assistant Professor at the Duke Eye Center, points out that we are entering an era of medicine where, for the first time, instead of just watching as patients lose basic abilities such as vision or movement, we can start to build devices that will help restore those abilities.  What an exciting new time!

It is often the case that researchers can get discouraged by costly failures and uncertain obstacles, but this is the important work that serves as a necessary reminder that every once in a while, when things work out, it is actually possible to give someone back the gift of sight.


Price, Jay. “Duke Fits First Patient in State History with ‘bionic Eye'”Newsobserver. N.p., 10 Sept. 2014. Web. 19 Oct. 2014.


2 thoughts on “Seeing the light

  1. Very interesting! As I was reading through your introduction of the disease, I was reminded of how hearing aids take over the job from damaged hair cells in the ear – this seems to be very analogous! I wonder if, with improvements in technology and materials a)the glasses could be shrunk down to a contact lens (Artemis Fowl style) and b) it could actually allow people to perceive ‘better’ than a normal eye!?!?! Could we start developing the ability to ‘see’ in the infrared or other usually non-visible spectrums? Exciting stuff!


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