Prescription glasses correct poor vision, while sunglasses protect the eyes from the sun's harmful ultraviolet (UV) rays. Both types of specs can be made from polycarbonate, a material first developed for use in the aerospace industry. Polycarbonate is more durable, lighter and thinner than regular plastic. These lenses, however, are just as susceptible to scratches as non-polycarbonate ones. You can repair a scratched polycarbonate lens yourself using tools and supplies commonly found in your home.
Spray the scratched polycarbonate lens with lens cleaner. Wipe the area, using a slow circular motion, with the edge of a lens tissue. Continue wiping until all of the lens cleaner has been wiped off.
Apply toothpaste to the tip of your index finger. Place the tip of your index finger on the lens, to the side of the scratch. Press down lightly on the lens as you drag your finger along the length of the scratch, leaving a trail of toothpaste. Lift your finger off the lens once you reach the other side of the scratch. Wipe your finger off on a paper towel.
Place the edge of a soft cloth against the lens, to one side of the scratch. Press down lightly on the lens as you drag the cloth along the length of the scratch. Reverse direction once you reach the other side of the scratch. Repeat this procedure four more times. Let 10 minutes pass before continuing.
Wet another soft cloth in cold tap water. Wring the cloth out. Apply the edge of the cloth to the area that was scratched in the same manner as before. Repeat the procedure again, only this time with the edge of a piece of lens tissue.
Don't use flavoured toothpaste; the granules providing the flavour are too abrasive and can scratch the lens.