If you're caught without your reading glasses, or you encounter some terrifically fine print somewhere, you have two options: curse your abnormal retina design or pinch your fingers together. The latter is like adjusting the f-stop on your eyeballs.
Instructables poster mikey77 shows us how it's done, using three fingers -- the thumb joined up against an index finger, with a middle finger forming the base -- to create a small hole through which to see tiny things more clearly. It's obviously not for lengthy reading, but it can help in a pinch (sorry). Here's how it works:
You are effectively creating a pinhole lens. This gives a slight magnification and significantly increases your depth of field (the range that is in focus). It does this by greatly limiting the amount of light going through the lens in your eye. It is like adjusting the F stop in a camera.
Tried this out? Got another last-ditch reading and vision tip?
How To Make Instant Reading Glasses [Instructables]