Many eyeglasses and sunglasses are made out of plastic. Plastic can scratch quite easily, and scratched lenses are more than an annoyance--they can affect your ability to see objects clearly. Restoring clear vision doesn't mean you need to buy a new pair of glasses; you often can remove scratches from plastic lenses.
Apply a thick coating of glass etching compound to both sides of your plastic lenses. Let the cream sit for five minutes, then wash it off with cold water. This alone may remove many or all of the scratches.
Apply liquid furniture polish to a rag, then rub it on the lenses. Wash with warm, soapy water, then repeat. This technique is especially useful if the scratch coating is peeling off.
Apply metal polish, which often works on even badly scratched plastic. Place the polish on a soft cloth, then rub it on the lenses for three to four minutes. Wash and dry the lenses.
Rub cigarette ashes into deep scratches, then rinse the lenses. Repeat twice. This method generally isn't as effective as the methods listed above.
You cannot remove scratches from glass lenses. The techniques listed above should be used only on plastic lenses.