In the OR today I saw a vitrectomy- the removal of the vitreous fluid from the posterior chamber of the eye, a surgical treatment for retinal detachment. As I observed this surgery and saw the macula live and very clearly for the first time something hit me (not a scalpel). It is surprising how humble a structure the macula is, especially considering how powerful it is. It is a square centimeter or so (no bigger than your pinky nail) but it receives all the light from the world that will eventually be processed into "sight". Without the macula one is essentially blind (peripheral vision will be spared, but try crossing the street using only your peripheral vision). It is really so small and so simple appearing, at least grossly, it almost looks indistinguishable any square centimeter of tissue, but it is oh so much more talented! As I was looking at this through the ophthalmologist lens, I found it amazing to consider that this little bit of mild mannered tissue catches light! Not only that it transforms it into a patterned electrical signal. How marvelous! This little bit, this tiny tiny bit of tissue can even sort wavelengths of light, weigh and average the intensity of the inputs and send it off in a ordered pattern that will eventually be critical for survival. Think about what that means in the most basic sense, electromagnetic fields can be sensed by carbon based tissues. How gorgeous! Even more so to consider that this little piece tissue came about organically, spontaneously. It is fun to speculate how this came about, why should sensing light matter to ocean life (where photoreceptors have been presumed to originate)? Theories abound, but the truth remains unknown. So it is that a structure appearing so small to the naked eye makes it possible to view the ends of the cosmos. There is lesson in there somewhere...
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