Anonymous wrote:As someone who has serious eye issues, I think this is a valid excuse.
Former professor @ Georgetown here and that would definitely be considered a valid excuse... especially for an assignment that isn't of critical urgency.
Your email should reflect everything you've written in this post -- if your professor pushes back, simply state that you'll send him/her the receipt from your visit (however, I don't believe that will be necessary).
Don't listen to the PP who said that it was a poor excuse, they've obviously never worked as a professor before.