Conjunctivitis%20-%20allergic,%20seasonal%20-and-%20perennial%20(pediatric) Treatment

• Eg Emedastine, Levocabastine, Nedocromil
• 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 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 (Oral)

• Eg Cetirizine, Chlorpheniramine, Hydroxyzine, Loratadine 
• 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

Antihistamines/Mast Cell Stabilizers (Ophthalmic)

• Eg Alcaftadine, Azelastine, Bepotastine besilate, Epinastine, Ketotifen, Olopatadine
• Have both mast-cell stabilizing and antihistaminic activity
  • Binds 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 & redness) and prevent recurrence of allergic conjunctivitis
• Fast-acting, effective and generally well tolerated

Corticosteroids (Ophthalmic)

• Used for the treatment of severe and chronic ocular allergy
  • Block inflammatory pathways that perpetuate the persistent and chronic forms of ocular allergy

• 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

• Relieve symptoms fast
• Should only be used for a short period of time (≤2 weeks) and under the guidance of an experienced ophthalmologist
  • Chronic use of topical steroids is associated with glaucoma, cataract formation, and corneal/conjunctival infection
  • Lowest potency and frequency that relieves patient’s symptoms should be given

Lubricants (Ophthalmic)

• Consist of saline solution combined with wetting and viscosity agents, which is used 2-6 times per 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

• 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.

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

• 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, 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

Nonsteroidal Anti-inflammatory Drugs (Ophthalmic)

• Eg 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, 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

• Trial of avoidance may identify antigens
• Skin testing or allergen challenge (serum antigen specific IgE antibody measurements) 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
• Reduce or avoid use of contact lens during seasonal flare-ups
• 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
• Sensitive patients should attempt to limit exposure to outdoors during times of high pollen count or other allergen counts

Cold Compress

• Causes vasoconstriction which can improve patient comfort by reducing itching

Principles of Therapy

• Repeated administration of specific allergens in patients with IgE-mediated conditions to provide protection against allergic symptoms associated with exposure to these allergens
• Only intervention that alters the natural history of allergic rhinoconjunctivitis
• Activates regulatory T cells, thereby altering humoral response to allergens by increasing CD8+ T cells and IL-10, and reducing IL-13 production
• Indicated for patients with the following:
  • Evidence of specific IgE antibody to allergen (positive allergy test results)
  • Any of the following:
    • Clinically diagnosed with both allergic rhinoconjunctivitis & asthma
    • Required medications
    • Poor response to avoidance measures
    • Adverse effects to medications
• Initial dose should be performed in a medical facility by a trained personnel 
• Recommended course is usually 4-5 years

Subcutaneous Immunotherapy (SCIT)

• Efficacy is comparable to that of nasal glucocorticoids
• Limited by frequent injection on regular basis and small risk of anaphylactic reactions

Sublingual immunotherapy (SLIT)

• A more viable treatment compared to SCIT as self-administration is encouraged with this form
• Use should be limited to those who can tolerate systemic reactions and its treatment 
• Auto/self-injectable Epinephrine should be prescribed to all patients receiving SLIT
• Has been associated with mild oral & GI symptoms & less risk for anaphylaxis compared to SCIT