Olopatadine hydrochloride is primarily used as an antihistamine in ophthalmic solutions to treat allergic conjunctivitis. It works by inhibiting the release of histamine from mast cells, thereby reducing symptoms such as itching, redness, and swelling of the eyes. The solution is applied directly to the eyes, providing quick relief from discomfort caused by allergens like pollen, pet dander, or dust. It is also effective in managing other eye-related allergic conditions, offering a non-invasive and convenient treatment option for patients. Additionally, its dual-action mechanism, which includes stabilizing mast cells and blocking histamine receptors, makes it a preferred choice for long-term management of ocular allergies.