But wearing dirty glasses can be more than just annoying. “First off, dirty lenses can cause eye strain and headaches — not fun,” says Dr. Janice Fan, an optometrist at 414 Eyes in Milwaukee.

If you wear glasses, you've probably used just about any soft fabric as a cleaning cloth in a pinch. The problem? Wiping your lenses on your T-shirt or any old fabric can worsen smudges.