Conjunctiva forms the mucous membrane component of the ocular surface and it is continually exposed to a wide variety of airborne antigens. In sensitized individuals, pollen, plant, house dust mite HDM) or animal dander allergens dissolve in the tear film, cross the conjunctival epithelium and activate substantia propria mast cells leading to the prevalent, unpleasant but not sight-threatening conditions of seasonal SAC) or perennial allergic conjunctivitis PAC). The cardinal symptom of SAC/PAC is itchiness. Signs of hyperaemia, chemosis, micropapillae and thin mucous discharge may be present but often no clinical signs are apparent. SAC is prevalent, a recent epidemiological survey noted that up to 40% of 13±14-year-olds worldwide reported the above symptoms [1]. In the UK, allergic conjunctivitis represents a leading cause of acute red eye presentation to both hospital and general practitioners [2].

Accurate diagnosis of SAC and PAC is critical, subsequent allergen identification through skin prick testing SPT) is ideal. Although principally a research tool, allergen specific conjunctival provocation ASCP) may reveal sensitivity to allergens not identified by SPT [3], it also forms the basis of many therapeutic intervention studies. Symptomatic measures such as allergen avoidance, reducing domestic exposure to HDM, relocating to an airconditioned atmosphere or wearing occlusive glasses are effective but often under-utilized measures. Tear film allergen may be diluted by normal saline or liquid tear drops, this alone may provide almost complete symptomatic relief and accounts for the high placebo effect observed in placebo-controlled therapeutic intervention studies [4]. Vasoconstriction using cold compresses or topical combinations of sympathomimetic and histamine