Olp 5 ml in one study, one drop of Olapatadine was clinically and statistically superior to 28 dronps of nedcromill in reducing itching associated with allergic conjunctivitis. Selective H1-receptor antagonist and inhibitor of histamine release from the mast cell. Reduces ocular symptoms of allergic conditions, such as inflammation, itching, watering and burning. Interacts least with natural membranes making it more comfortable for ocular tissues. Exerts mast cells stabilising effects, thus has a both symptomatic and preventive effect.