I love that comic! Thanks for posting that! I am a big fan of Derpy Hooves and RainbowDash and pegasus in general, and I've aways wondered how Derpy got her derp and how Derpy got her weird bubbles cutie mark! Thanks for explaining it in this comic! Again, I love it! Post more comics soon!
And so... Her vision was permanently impaired. Failing to determine what is near and what is far anymore, Derpy Hooves, as her classmates began naming her that very day, continued to derp up her major life decisions from then on.
Doctor Hooves, frustrated with being late yet again (possibly due to being a terrible driver in control of time-space technology) gave up on his quest to try and save Derpy from being the decidedly clumsy pegasus we know today. He would not tell Derpy of this event, and with any luck, she wouldn't even remember. She was fun to be around as she was, and he even preferred not to think of how things might have been different if Ditsy Doo hadn't become so derpy.