The other day I had to get a eye check for a minor adjustment to my lens prescription. Bryan Vincent did my eye exam and returned a clean bill of health and a slightly altered script for new eyeglass lenses. This of course, as always was an opportunity to make some photographs.
The image immediately above is a phoropter, the device you look through during an eye examination so your optometrist or ophthalmologist can determine what kinds of optical correction needs to be made for prescription lenses. I grabbed this frame with an iPhone and an app called Hueless, the best B&W photography app available for the iPhone.
Seeing as how my eyes were dilated for the exam, I figured it would be a neat opportunity to image the retina at the back of my eye. So, with the help of my technician, Drew Ferrell, we went back to the lab where I have a Heidelberg Spectralis Optical coherence Tomography (OCT) machine from Heidelberg Engineering. This image and the image at top are infrared images of the outside of my eye showing the totally dilated pupil, iris and sclera.
Moving inside the eyeball, we have an image of my retina. For some reason, its always a little disconcerting for me to glimpse typically unseen parts of your own biology, even when things look good. The dark circle at the right of the image is my optic nerve, where all of the retinal ganglion cells leave the retina carrying signals computed by the neural retina before sending those data onto the visual cortex and subcortical areas where unconscious aspects of visual information are processed. It turns out that the vast majority of ganglion cells in the retina project to these places and its the minority of ganglion cells that process conscious visual information. This has implications for those who claim to understand how the retina processes information and rescue vision loss. You can also see the vasculature of the retina that supply the retina with blood as well as remove the deoxygenated blood from the retina out through the opthalmic veins.
This image of OCT data from my retina was captured previously and used as a basis for the introductory figure in this entry. The elevated portion is a mapped out rendering of the thickness of retina showing the layers of the retina and vascular choroid underneath it. This is the sort of imagery that clinicians are increasingly using to make diagnoses of various sorts.
Being able to visualize real biology like this is always stunning, and it helps to inspire some of the work that I am involved in. The retina seems like a magical device, but its important to note that our retina in many ways is much less sophisticated than other retinas in the animal kingdom like birds, fish and turtles. That said, its still a remarkable data processing device and efforts in our lab, the Marc Laboratory for Connectomics are the best approach for understanding 1) which cell classes there are in the retina and 2) how those cell classes are connected to one another. The outcome from these efforts will help us to understand how the retina is constructed and algorithms for understanding how neural systems process information that could be used for all sorts of data processing applications from the design of bionic retinas to new methods of biologically inspired computing. Its a pretty exciting time.