We have some Christmas cards that have a picture on the front of a blank-faced snowman. Then inside someone has put two chunks of coal in the snowman’s face and he’s shouting “I can see! I can see!”
That’s how most people think of the “gift of sight.” Having those eyes in their sockets and healthy and seeing is – obviously – really important. Seeing, however, is more complex than just eyes, involving much of the brain. Those eyes do, however, provide something like 80% of the sensory input to the brain.
A lot of people understand we actually perceive sight (we “see”) in the brain. The message of sight travels from the eye to the brain in two primary nerve bundles: one sees detail and color, the other sees motion. It is the interplay of those two nerve bundles (“pathways”) that, when operating properly, give us the stable bilateral sight (binocularity) that gives our brains the best three-dimensional visual information possible.
When those pathways don’t operate in concert together, vision can become like a bad concert. The strings are in one place in the music, the brass in another place, and who knows what the percussionists are doing? That’s a little simplistic, of course, but when the two primary pathways don’t cooperate, the signal to the brain becomes intermittent – sketchy – part-time. Imagine trying to read like that. Or catch a baseball. Since this involves brains, not eyeballs as such, glasses don’t fix everything. That’s why we treat these problems with therapy. So, when you see the snowman with coal for eyes, remember that although he thinks he can see, he really can’t see. No brain in the top snowball. Bummer.