How to clean tear stains on cats:
1. If a cat has severe tear stains, you can mix starch and boric acid powder with a little water and gently brush it onto the areas with tear stains.
2. If the tear stains on your cat are not too severe, you can wipe them with clean water or diluted salt water every day. If you persist for a period of time, the tear stains on your cat will improve.
3. If the cat's tear stains are caused by blocked tear ducts and ingrown eyelashes, a minor surgical procedure is needed to correct them. 
Reasons for tear stains in cats:
1. If a cat eats too much salt in its daily diet, it will irritate the cat's eyes, causing more tears and resulting in tear stains.
2. If a cat has eye inflammation, it will also cause increased eye discharge, which will constantly soak the fur around the cat's eyes and lead to severe tear stains.
3. Some cats are born with more tearing eyes, which is related to the nasolacrimal duct and lacrimal gland, and is a congenital factor.
