Opticrom Allergy Eye Drops Opticrom Allergy Eye Drops provide effective relief from irritated eyes caused by airborne allergies in just two minutes. The active ingredient, sodium cromoglicate, works by blocking the release of histamine, your body's natural allergic response chemical that causes the reaction. Opticrom Allergy Eye Drops can be used to treat & prevent hayfever & eye allergies from mould, dustmites & animal dander, conditions referred to as 'perennial allergic conjunctivitis'. Signs of an allergic reaction include itchy, watery, red or inflamed eyes & puffy eyelids.