Conjunctivitis%20-%20allergic,%20seasonal%20-and-%20perennial Treatment
Pharmacotherapy
Antihistamines (Ophthalmic)
- Eg Alcaftadine, Emedastine, Levocabastine
- Compete for the histamine receptor sites
- In human conjunctiva, stimulation of H1 receptor mediates symptoms of pruritus while H2 receptor is involved in vasodilation
- Reduce itching and vasodilation
- Emedastine was shown to be more effective than Levocabastine in decreasing chemosis, eyelid swelling, and other signs and symptoms of seasonal allergic conjunctivitis
- A selective H1 antagonist with no adrenergic, dopaminergic or serotonergic effect
- Emedastine was shown to be more effective than Levocabastine in decreasing chemosis, eyelid swelling, and other signs and symptoms of seasonal allergic conjunctivitis
- Provides immediate ocular relief as compared to oral antihistamines
- May be used as monotherapy or in combination with decongestants/vasoconstrictors in treating signs and symptoms of allergic conjunctivitis
- Antihistamine/vasoconstrictor preparations may be used for short-term treatment (≤2 weeks) of acute allergic conjunctivitis
- Antihistamine with decongestant/vasoconstrictor should not be used for >2 weeks without medical advice
- Should not be used for >6 weeks without medical advice
- Prolonged use of antihistamines that are nonselective may cause ciliary muscle paralysis, mydriasis, and photophobia, especially when used by patients with lighter irides
- May also cause angle-closure glaucoma particularly in patients who are at risk (ie history of narrow-angle glaucoma, patients with narrow angles)
Antihistamines/Mast Cell Stabilizers (Ophthalmic)
- Eg Azelastine, Bepotastine, Epinastine, Ketotifen, Olopatadine
- Have both mast-cell stabilizing and antihistaminic activity
- Bind to H1 and H2 receptors, stabilizes mast cell, and down-regulates inflammatory markers that affects early and late phases of the conjunctival allergic response
- May be used for either acute or chronic diseases
- Relieve acute symptoms (eg ocular itchiness and redness) and prevent recurrence of allergic conjunctivitis
- Fast-acting, effective and generally well tolerated
- For patients with SAC, begin treatment at least 2-4 weeks prior to pollen season for optimal effectivity
Antihistamines (Oral)
- May be used as adjunctive therapy for moderate to severe allergic conjunctivitis
- Useful in cases accompanied by non-ocular allergies (eg allergic rhinitis)
- Inferior to ophthalmic antihistamines primarily due to 1- to 2- hours delay from systemic administration to delivery to ocular tissues but has longer duration of action
- More likely than topical antihistamines to cause side effects
- May be associated with drying of mucosal membranes and decreased tear production, especially in patients with concomitant dry eye
Nonsteroidal Anti-inflammatory Drugs (Ophthalmic)
- Eg Diclofenac, Ketorolac
- Inhibits the activity of cyclooxygenase blocking the production of prostaglandins
- Helps reduce ocular signs and symptoms like itching or conjunctival hyperemia
- Do not mask ocular infections, affect wound healing or intraocular pressure (IOP), nor contribute to cataract formation
- Eg Naphazoline, Phenylephrine, Tetrahydrozoline
- Sympathomimetic agents
- Decreases vascular congestion and eyelid edema but do not affect allergic response
- Usually used in combination with ophthalmic antihistamines
- Have been shown to have synergistic effect
- Based on studies, Naphazoline plus Antazolin or Pheniramine were comparable in decreasing the signs and symptoms of allergic conjunctivitis
- Chronic use (>10 days) may cause conjunctivitis medicamentosa
Mast Cell Stabilizers (Ophthalmic)
- Eg Cromoglicic acid, Lodoxamide, Nedocromil, Pemirolast
- Inhibit degranulation of mast cells which limits the release of inflammatory mediators and platelet-activating factor
- Used for prevention of symptoms and for conditions that are recurrent or persistent
- Have slower onset of action as compared to antihistamines
- Effects of Cromoglicic acid are evident 2-5 days after the initiation of the therapy with maximum improvement of ocular symptoms after 15 days
- Requires multiple applications everyday to show effects
- Most useful in the seasonal management of chronic allergic diseases of the eye
- More effective when used prophylactically with loading period and administered before triggering of allergic reaction
- Usually given to patients with moderate symptoms, after an ophthalmic decongestant have been administered to provide immediate relief
- Studies have shown that Lodoxamide is more effective than Cromoglicic acid in reducing eosinophil activation, and clinical signs and symptoms
- Pemirolast was shown to specifically inhibit mast cell degranulation, thus preventing the release of chemical mediators like histamine
- May also help in improving symptoms of allergic rhinitis
- Generally well tolerated and may be used as long as needed
Lubricants (Ophthalmic)
- Consist of saline solution combined with wetting and viscosity agents, which is used 2-6x/day as needed
- Non-preserved formulations are recommended if will be used frequently to prevent allergic reactions secondary to preservatives
- Assist in the removal and dilution of allergens that come in contact with the eye surface
- Do not alter the pathophysiology of the disease but treat co-existing tear deficiency
- Washing the eyes frequently with water decreases the integrity of the layer of tears, hence, artificial tears may be used instead
- Numerous lubricants that differ by class, osmolarity and electrolyte composition are available
- Many ophthalmic lubricants are available. Please see the latest MIMS for specific formulations.
Corticosteroids (Ophthalmic)
- Should be given and supervised by an ophthalmologist
- Reduces inflammatory cytokine production, mast cell proliferation and cell mediated immune response
- May be considered for use in the treatment of severe and chronic ocular allergy
- Block inflammatory pathways that perpetuate the persistent and chronic forms of ocular allergy
- May be used when patient’s symptoms have not responded to other agents
- 1-2 weeks course can be added to antihistamine/mast cell stabilizers if symptoms were not controlled
- Lowest potency and frequency that relieves the patient’s symptoms should be given
- Should only be used for a short period of time (≤2 weeks)
- Chronic use of topical steroids is associated with glaucoma, cataract formation, and infections of the cornea and conjunctiva
- Inappropriate use in herpes simplex, fungal, and other viral or bacterial keratitis may cause complications that may threaten vision (eg corneal melting, perforation, and scarring)
Immunotherapy
- Used in patients with atopic disorders like SAC, PAC, allergic rhinitis, or asthma
- Desensitizes a patient against a specific allergen
- However, ocular symptoms takes longer than nasal symptoms
- Topical Cyclosporine or Tacrolimus may be used in severe conditions
- Cyclosporine A limits type IV allergic response thereby reducing infiltration of eosinophils
- Tacrolimus reduces action of T cells
- Giant papillae and corneal lesions as well as total sign and symptom scores are reduced in refractory disease
- Needs careful monitoring by a specialist
- Its use is limited by cost, long-term patient commitment and the possibility of anaphylaxis
Non-Pharmacological Therapy
General Eye Care Measures
- Avoid excessive eye rubbing
- May cause worsening of symptoms and degranulation due to mechanical disruption of mast cells
- Apply cold compress to reduce symptoms such as eyelid and periorbital edema
- Causes vasoconstriction which can improve patient comfort by reducing itching
- Reduce or avoid use of contact lens during seasonal flare-ups
Identification of Trigger Factors
- Trial of avoidance may identify antigens
- Skin testing or allergen challenge may be useful for identifying specific problematic antigens but are rarely needed
Avoidance of Trigger Factors
- Eg closing windows, filtering air, removing pets and stuffed toys, vacuuming and dusting regularly, etc
- Mainstay of managing allergic conjunctivitis
- Use of goggle-type glasses are recommended during pollen-flying period
- Sensitive patients should attempt to limit exposure to outdoors during times of high pollen count or other allergen counts
- House mites are a common allergen and can be reduced by using dust mite-proof encasings on pillows and mattresses, and washing sheets in hot water
- Washing clothes frequently and bathing before bedtime may be helpful
Surgical Intervention
- Tarsal Conjunctival Resection (including the papillae)
- Performed when symptoms are not alleviated by pharmacological therapy and progressive conjunctival papillary hyperplasia worsens the corneal epithelium disorder
- Therapeutic effect is observed immediately though symptom recurrence may occur