Used primarily as a mast cell stabilizer in ophthalmic formulations to prevent and treat allergic conjunctivitis. It works by inhibiting the release of histamine and other mediators from mast cells, thereby reducing itching, redness, and swelling associated with eye allergies. Commonly prescribed in the form of eye drops for seasonal allergic conditions, especially in patients with a history of vernal keratoconjunctivitis or other chronic ocular allergies. It is favored for its prophylactic effect, requiring regular use to maintain effectiveness, and is generally well tolerated with minimal systemic absorption.