Conjunctivitis%20-%20allergic,%20seasonal%20-and-%20perennial Treatment

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
• 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

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

• 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