Your eyes are tiny spheres of wonder. They are home to your body’s busiest muscles, its most active neurons and the most transparent cell tissue of any you possess. These intricacies generally go unnoticed when you’re healthy and everything’s running smoothly. But behind the scenes, your brain can spend more than a third of its power parsing what your peepers send along.

I didn’t know any of this when I went in for a recent eye exam, my first in years. I had been coming home from work with itchy, bloodshot eyes. The blurriness of small type on screens suggested that I’d need glasses soon. As expected, I walked away from the exam with a new set of frames.

But the doctor