Download - If2
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Allergy
• An abnormally high sensitivity to certain substances, such as pollens, foods, or microorganisms is called as allergy.
• Substances causing allergy : Allergens
May be I am allergic to
flowers
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Ocular allergy :Allergic conjunctivitis
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Allergic Conjunctivitis : Causes
POLLEN
PET DANDER
POLLUTION
DUST MITES
MOLDS
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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
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Allergic Conjunctivitis : Signs and SymptomsItching : Is the hall mark of allergy
Redness
Teary, watery eyes
Stinging and burning sensationFeeling of grittiness and discomfort
Photophobia (extra-sensitivity to light)Lid Swelling
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Allergic Conjunctivitis : Manifestation
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Allergens Ocular Surface Allergen binds with IgEon 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
ProstaglandinsLeukotrienesPlatelet-activating factorsCytokines (TNF)Chemokines (IL-8)
Redness, swelling Infiltration of eosinophils & neutrophils
Calcium enters the cells
Mast cell degranulation
Release of Mediators
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Primary
Mediator
H1 receptor on nerve cells H2 receptor on blood vessels
Mast cell Degranulation
Histamine released
Itching Redness and Swelling
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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
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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
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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
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“The goal of treatment for allergic conjunctivitis is to effectively resolve clinical signs and symptoms, and improve quality of life.”
– Jose Güell, MD
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Allergic Conjunctivitis
Conventional Medical Management Overview
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Drug Categories : IndicationsDrug Category Example Indication
Vasoconstrictor Naphazoline For managing redness
Steroids Loteprednol For sever conditions like VKC , manage severe inflammatory conditions
Antihistamines Levocabastine ,
Emedastine
When intensity of itching is higher , antihistamines are preferred.
Mast Cell Stabilizer Sodium cromoglycate , nedocromil
For prophylaxis , prevention of allergy loading doses are administered, also along with antihistaminic agents
Dual Acting agents Olopatadine , azelastine , Epinastine , ketotifen
For controlling signs and symptoms of allergic conjunctivitis
For temporary relief from symptoms
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Ideal Ocular Anti-allergic Agent : Features
• Must have both mast cell stabilizing and antihistaminic activity
• Fast Acting • Long lasting relief• Soothes the eyes• Convenient dosing
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Ocular Allergies : Require Prompt
Attention and Action
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• Mast-cell mediators, such as tumor necrosis factor, stimulate the expression of adhesion molecules on the surface of the conjunctiva.
• Olopatadine decreases adhesion molecule expression demonstrating potent mast-cell stabilizing activity
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Conclusion :
Olopatadine is significantly more effective than epinastine in controlling itching, redness and chemosis associated with allergic conjunctivitis in the CAC model.
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Adverse Effects
• The following ocular adverse experiences have been reported in less than 5% of patients:
• Blurred vision, • Burning or stinging, • Dry eye, • Foreign body sensation, • Hyperemia, hypersensitivity, • Keratitis, • Lid edema
PDR 2006
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Highlights
Potent mast cell stabilizing abilityOlopatadine is the first topical ophthalmic dual acting anti-allergy agent that has clinically shown mast-cell stabilization in human eyes.
Fast Acting Reduces itching symptoms within 3.5 minutes of administration to the eyes
Long lasting relief: Dual mechanism of action gives an immediate
and a long lasting relief.
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