The first one is an old favorite, the next two are new--found through a former coworker's Facebook. The last one talks about Lasik and mentions other optical things--though in optometry at least (I don't know what those crazy ophthalmologists do) we say "minus" and "plus," not "negative" and "positive." If your glasses Rx is -2.25-0.50x120, you say "minus two point twenty-five, minus point five, at one-twenty." And "negative five is pretty much blind" is utter nonsense--assuming your vision is correctable, you're not even legally blind at -5.00. I'm -7.50 in my right eye--I see less than 20/400 without lenses (the large E projected in the exam room? looks like jumbled semitransparent blocks, basically), but I correct to 20/20 and am therefore definitely not "pretty much blind."
Nitpick, nitpick, nitpick. It's a great song anyway.