How to Clean Glasses With a Stain Inside the Lens

Remove your glasses and run the lens under warm water. Use your finger to gently rub the stained area.

Add a few drops of mild, non-abrasive liquid soap. Rub it gently on the lens and then rinse it with warm water.

Use a lint-free lens cloth to dry off your glasses. Do not use a cloth that's not recommended for lenses. It could scratch the surface.

Spray the lens with lens cleaner if you can still see some of the stain or if your lenses are smudged from the cleaning process.

Wipe off the lens using a dry side of your lint-free lens cloth. Your lens should now be crystal clear and stain free.