You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Olopatadine is: and explain in detail?
Ref: Clinical Oculor Pharmacology, 1st ed. pg. 257* Olopatadine hydrochloride is an antihistamine (as well as anticholinergic and mast cell stabilizer)* It is used as eye drop to treat itching associated with allergic conjunctivitis.* Side effects include headache, eye burning and/or stinging, blurred vision, dry eyes, foreign body sensation, hyperemia, keratitis and taste perversion.