I first found out that I was nearsighted in fourth grade. My assigned seat was in the second-to-last row of the class, and I was constantly peering at the fuzzy words on the board and getting up for a better look.
When I got my first pair of glasses, I couldn't believe that normal people walked around every day seeing the world like this. I didn't have the analogy back then, of course, but it was exactly like the difference between HDTV and the normal broadcast standard. Everything was so clearly delineated, as if outlined with sharp boundaries. The distinction in the environment was a shock to me. Things separated themselves from each other with lines of light and color completely alien to the watercolor washes and impressionistic blurs I had always lived with.
In the eighth grade I got contact lenses, and became perversely proud of how poor my vision was. My relatively good right eye was 20/100. My almost useless left eye was off the chart; the eye doctor's report didn't even use numbers for it. "Four fingers," it said, indicating that I could distinguish four fingers held up against the light, even though I couldn't make out any of the letters or numbers.
Things haven't gotten much worse in the ensuing decades. I went to the doctor today and got a slight uptick in my prescription. The one consolation of nearsightedness is that it delays the onset of presbyoptera, apparently; I've yet to experience problems at reading distance. But for the rest of my life I'll be completely dependent on these little concavities of plastic, and the various cases and solutions that keep them wearable.
I'll always be grateful for that moment of clarity when I saw the world for the first time the way people with normal sight see it every day. Even though I've spent nearly every waking hour since with lenses that give me that experience, that distinctiveness still feels artificial to me -- as if someone is projecting a sharper, hyperfocused version of the world upon my brain.