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Seasonal Allergic Conjunctivitis (SAC) Exposure to seasonal allergens like pollen Perennial Allergic Conjunctivitis (PAC) Continuous exposure to persistent allergens such as house dust mites Mild form of allergy Vernal keratoconjunctivitis (VKC) Due to severe hot conditions , more common in men . Itchy eyes , with mucous strands seen in the morning after sleep. Increase in goblet cells ( special type of cells in conjunctiva) Giant Papillary Conjunctivitis (GPC) Results from trauma caused by contact lens edges, or post- operative sutures . Allergic Conjunctivitis : Types
Allergic Conjunctivitis : Signs and Symptoms Itching : Is the hall mark of allergy Redness Teary, watery eyes Stinging and burning sensation Feeling of grittiness and discomfort Photophobia (extra-sensitivity to light) Lid Swelling
Allergic Conjunctivitis : Manifestation
Allergens Ocular Surface Allergen binds with IgE on mast cell Leads to mast cell activation Preformed Mediators Histamine Chymase Tryptase Proteases Itching , Redness , Swelling Degradation of neighboring cells Inflammatory cells accumulation Newly Formed Mediators Prostaglandins Leukotrienes Platelet-activating factors Cytokines (TNF) Chemokines (IL-8) Redness, swelling Infiltration of eosinophils & neutrophils Calcium enters the cells Mast cell degranulation Release of Mediators
H1 receptor on nerve cells H2 receptor on blood vessels Mast cell Degranulation Histamine released Itching Redness and Swelling
Mediators of Allergy :Roles
Histamine : Itching, redness, edema
Prostaglandins : Sensitized nerves, enhanced pain, edema and redness
Leukotrienes : Chemotaxis, edema and vascular permeability
Chemotactic factors : Recruitment of eosinophils and neutrophils leading to tissue destruction
Role Of Adhesion Molecules
Adhesion molecules are found on the surface of the conjunctiva and on the endothelium of blood vessels,
Help to attract eosinophils, basophils and neutrophils, and their migration into the tissue.
High expression of ICAM1 will lead to large number of inflammatory cells attacking the corneal epithelium.
These cells then rupture to release toxic mediators of allergic response.
E.g of adhesion molecule : ICAM 1
Conjunctival intercellular adhesion molecule 1
Allergic Conjunctivitis :Reduced QOL
Allergy sufferers experience QoL reductions in general health , well being , in their day-day routine activities and specific aspects of vision as a result of their Allergic Conjunctivitis
“ The goal of treatment for allergic conjunctivitis is to effectively resolve clinical signs and symptoms, and improve quality of life.” – Jose Güell, MD
Allergic Conjunctivitis Conventional Medical Management Overview
Drug Categories : Indications For prophylaxis , prevention of allergy loading doses are administered, also along with antihistaminic agents Sodium cromoglycate , nedocromil Mast Cell Stabilizer For controlling signs and symptoms of allergic conjunctivitis For temporary relief from symptoms Olopatadine , azelastine , Epinastine , ketotifen Dual Acting agents When intensity of itching is higher , antihistamines are preferred. Levocabastine , Emedastine Antihistamines For sever conditions like VKC , manage severe inflammatory conditions Loteprednol Steroids For managing redness Naphazoline Vasoconstrictor Indication Example Drug Category
Ideal Ocular Anti-allergic Agent : Features
Must have both mast cell stabilizing and antihistaminic activity
Long lasting relief
Soothes the eyes
Ocular Allergies : Require Prompt Attention and Action
Mast-cell mediators, such as tumor necrosis factor, stimulate the expression of adhesion molecules on the surface of the conjunctiva.