Improperly adjusted plastic eyeglasses can be uncomfortable and cause eyestrain. Most of the time, you can find a nearby optician who will adjust your eyeglass frames at no charge; however, you can also adjust plastic eyeglass frames yourself. It's best to only make small, infrequent adjustments so you don’t damage your frames.
Adjust the nose pads if your frames have them. Nose pads are attached to eyeglass frames with small metal brackets. If your glasses are sitting to high on your nose, gently bend the nose pads outward a little. If the glasses are too low, bend the nose pads inward.
Heat the temple tips with a hair dryer or hot water for 20 seconds if your plastic eyeglasses are too loose or too tight. The temple tips are the part that bends around your ears to hold the glasses in place. Hold the glasses by the nose piece and gently bend the temple tips. Bend inward to tighten the frames and outward to loosen them. Run cold water over the temple tips to set the plastic in the new position.
Set the glasses right side up on a flat surface with the temple pieces open. Tap the frame gently. If it rocks at all, you will need to adjust the temples up or down. The temples are the straight sections connecting the front of your glasses with the temple tips.
Heat the temples with hot water or a hair dryer for 20 seconds. Gently bend the temple piece up or down as needed. Run cold water over the temple piece to set the plastic in place. Set the glasses on a table and check to see if the rocking has been eliminated. If not, continue adjusting the temples as described above.