If you wear plastic glasses, one of the most irritating things that can happen is if the frame doesn't fit perfectly on your face. The good news is you don't necessarily need to bring a pair of plastic framed glasses to a professional just because it doesn't sit quite right on the bridge of your nose. It is possible to adjust the frames yourself provided you are careful and have the right tools.
Stand in front of a mirror and look straight ahead. Put the glasses on and position the center of the lenses directly in front of your eyes. Remember where the glasses feel off balance and where you will need adjustments.
Warm up the frames by running the temple tips under hot water for no more than 20 seconds, or by using a hairdryer. Be careful to avoid allowing the frame to become too hot, as it could damage the plastic.
Make a small adjustment to the temple by gently bending or pulling at the plastic, and quickly run the adjusted area under cold water to set it in the new position.
Try the glasses on to check to see if they are balanced on your face. If more adjustments need to be made, repeat Steps 2 and 3.
If the glasses sit too low on the nose, adjust the bend on the temple tips so that the ends are bent closer toward the lens. If the glasses sit too high on the nose, adjust the bend on the temple tips so that the ends are straighter and point away from the lens. If the glasses are too loose, adjust the temples and tighten the screws in the hinges with a screwdriver so they bend inward toward your head for better grip. If the glasses are too tight, adjust the temples and loosen the screws in the hinges with a screwdriver so they bend more outward and away from your head for a looser grip. If the glasses are not sitting evenly, slightly raise or lower the temple arms according to which ear is higher than the other.
Be very gentle when adjusting your glasses, as the frames could break.