Even though anti-glare lenses rarely get any scratches, rough handling and consistent use can wear out the lens. However, you can remove the scratches easily in the following ways:
An etching cream removes any scratches from the surface of plastic lenses.
Gently rub the lens surface with carnauba wax using a paper towel or cloth.
It is better to get a new pair of lenses since these methods can damage the anti-glare coating.