system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't my eyes heal?

 So I can mend broken bones, I can heal cuts. I can fight off diseases, but once my eyesight started deteriorating at age 15 I have had to wear glasses. Why can't my eyes get better, or heal back to the good vision I had before?
gpt
Your eyes aren't 'broken' they are merely 'adapted'. Modern humans stare at close-range things much, much more than their hunter-gatherer ancestors, so the muscles they don't use naturally become weaker over time (subject to some genetic and random variation) resulting in poor eyesight at range, requiring correction.

You *CAN* train your eyesight to become better, over a long period of time, with special exercises and looking at particular patterns and things, but you'll never have perfect vision once you've lost it.