Gabrielle Woo, Cornell
One of the neat things about being a vet is that you are at once a general physician, pediatrician, dentist, radiologist and much more. Lately we have been concentrating on the ophthalmological aspect of vet medicine by examining eyeballs belonging to all sorts of animals. This is what Saunders Veterinary Dictionary says under ”eye”.
(noun): the organ of vision. In the embryo the eye develops as a direct extension of the brain, and thus is a very delicate organ.
This brief definition doesn’t do justice to one of the most complex organs in the body. Studying the eye in gross dissection entails a series of prosected dog heads with varying degrees of muscle and nervous tissue removed from the face. This is most useful for figuring out which muscle attaches where and does what, and which nerve runs through which hole in the skull and innervates which part of the eye.
But my favourite part comes when I look at a living animal armed with new information about how the eyes work. Why do horses blink when a fly buzzes near the skin around their eyes?
It’s an inborn reflex involving two cranial nerves, one sensory and another motor with a connection between them somewhere in your brain, and a ring of muscle around the eye. The teaching cats in the lab are forever rolling their eyes in frustration at my unsuccessful attempts to palpate their abdomens. This simple action requires a series of coordinated contractions and relaxations of over ten different muscles attached to and surrounding the eyeball. The sense of vision is even more complex and includes both cornea and lens to refract light into the back of the eye, where a host of specialized receptors convey information to the brain and higher cognitive processing occurs to generate an appropriate motor response to what was seen.
Now think about photographing an animal who is looking at me. The amount of muscle and nerve and brain coordination involved in this feat for both the animal and myself just blows my mind.
Are you beginning to see, too? Isn’t it incredible?