Treatment for Allergic Conjunctivitis

Over-the-counter medications

• Topical decongestants

  Reduce chemosis and conjunctival hyperemia by an alpha-adrenergic mechanism resulting in vasoconstriction. Sympathomimetic amines stimulate alpha receptors. Topical decongestants work within minutes (duration of about 2 hours). Dosing: qid.

  • Phenylephrine HCL
  • Naphazoline HCL
  • Toxymetazoline HCL
  • Tetrahydrozoline HCL (Visine)

  Side effects:

  • Rebound redness--can cause acute or chronic inflammatory conjunctivitis which can take several weeks to resolve after discontinuation the drug
  • Dilation of the pupil
  • Patient builds up tolerance to drug
  • Contraindicated in those with narrow angle glaucoma
  • Decongestants mask the signs and symptoms of allergic conjunctivitis

• Decongestant/antihistamine combinations

  Obviously, antihistamines would mildly suppress the immunological response. They help with itch more than straight decongestants.

  • Opcon-A (0.315% pheniramine maleate, 0.02675% naphazoline hydrochloride)
  • Vasocon-A (0.5% antazoline phosphate, 0.05% naphzaoline hydrochloride)
  • Naphcon-A (0.3% pheniramine maleate, 0.025% naphazoline hydrochloride)

  Chronic use of vasoconstrictors can lead to toxic, follicular reactions or possibly a contact dermatitis. (Reference: Soparkar CN, Wilhelmus KR, Koch DD, et al. Acute and chronic conjunctivitis due to over-the-counter ophthalmic decongestants. Arch Ophthalmol 1997; 155 (1):34-8.)

• Oral antihistamines

  All antihistamines (even nonsedating types) have a drying effect on the ocular surface. Antihistamines have atropine-like properties that decrease the tear production via the lacrimal gland. They could also be decreasing mucin production by the goblet cells.

  • Diphenhydramine (Benadryl)
  • Chlorpheniramine (Chlor-Trimeton)
  • Loratadine (Claritin)

  Be sure to check to see whether your patient is taking OTC antihistamines.

Prescription acute care drugs

• Topical antihistamines

  These drops work by competing with histamine for the H1 receptor sites. If the site is bound by an antihistamine, then histamine is denied the opportunity to begin the allergic cascade. Have unexplained vasoconstrictive properties. Topical antihistamines work well against lid myokymia (lid twitch).

  • Emadine (emedastine dirfurmarate 0.05%)--qid dosing; works immediately to reduce itch, redness, chemosis, and tearing.

  Side effects: Stinging, burning, headache, fatigue, nausea.

  Disadvantages: Do not prevent inflammation or release of histamine; short duration of action.

• Mast cell stabilizing antihistamine

  Dosing: bid (can try and decrease to qhs after several weeks of use). Side effects: eye burning/stinging, headaches, bitter or metallic taste.

  • Patanol (olopatadine hydrocholride 0.1% and 2%)
  • Zaditor (ketotifen fumarate 0.025%) OTC
  • Elestat (epinastine HCL 0.05%)
  • Optivar (azelastine hydrochloride 0.05%)

  Which is the best choice? Zaditor is now OTC. Both Zaditor and Optivar inhibit esosinophils which is not really needed in acute allergic conjunctivitis. Optivar has been shown to reduce the influx of inflammatory cells during the early and late phase of allergic reactions. For the most part, there is not a lot of difference between the medications. Optivar claims to be the cheapest prescription ocular medication since it is packaged in a 6 ml bottle.

• NSAIDs (Non-Steriodal Anti-Inflammatory Drugs)

  These aspirin-like drugs specifically inhibit the enzyme cyclooxygenase which blocks the production of prostaglandins from arachidonic acid metabolism. NSAIDs alter the patient's sensitivity to itch by raising the sensory threshold of peripheral nerve endings.

  Acular (ketorolac tromethamine 0.5%) is the only NSAID approved for the treatment of itch (as well as p/o cataract inflammation). Acular basically works as an analgesic to decrease pain. Onset of relief occurs within an hour. It is considered safe with few contraindications, although it does sting quite a bit. To relieve some of the stinging, Allergan formulated:

  • Acular LS--reformulated Acular; lower concentration 0.4%
  • Acular PF--preservative free, unit dose system (more expensive)

• Topical Steriods

  Topical steroids are particularly helpful in severe cases of VKC, AKC, GPC, and allergic contact dermatitis. They reduce the inflammatory response by:

  • Decreasing the production of prostaglandins and leukotrienes
  • Reducing capillary permeability
  • Suppressing lymphocyte circulation
  • Inhibiting mast cell degranulation, therefore, preventing the release of histamine

  Newer steroids tend to be used in allergy treatment. One such "newer" steroid is lotepredol etabonate, which is considered a site-specific drug. There is a transformation of the active drug to an inactive metabolite (cortienic acid) shortly after rendering a therapeutic effect. It is less likely than prednisolone acetate to cause IOP spikes and cataracts.

  Loteprednol etabonate 0.2% is Alrex;
  Loteprednol etabonate 0.5% is Lotemax.

  Lotemax and Alrex are approved for treatment of allergic conjunctivitis and are rarely prescribed alone. Use qid.

  Which works better--steroid or allergy drop? One study looked at Patanol vs. Lotemax and found Patanol to be better at relieving allergic symptoms.

• Oral antihistamines

  Oral antihistamines should be prescribed when patient has significant nasal problems. It might be wise to let the primary care physician handle this or refer to allergist to determine to what the patient is allergic. Insurance companies have stopped paying for prescription antihistamines.

  • Cetirizine (Zyrtec)--5 and 10mg tabs qd, syrup 1mg/1ml; Zyrtec-D
    Zyrtec does yield therapeutically effective concentrations of the drug at the anterior surface of the eye.
  • Fexofenadine (Allegra)--60 ms tabs po bid or 180 mg qd; Allegra-D
  • Desloratadine (Clarinex)--5 mg tab po qd

  Several studies over the past few years have found topical allergy drops to be more effective in relieving symptoms of allergic conjunctivitis than oral antihistamines. Concomitant use of a nasal spray plus a topical allergy drop (e.g., Flonase + Patanol) was more effective than a nasal spray (Flonase) + an oral antihistamine (Allergra) for overall treatment of signs and symptoms of allergic conjunctivitis.

• Intranasal sprays

  Topical intranasal corticosteroids are more effective than oral antihistamines in controlling nasal blockage. Long-term use of intranasal sprays can lead to the rare side effects of elevated IOP and cataracts.

  A review of nine randomized studies (using Livostin and Optivar) found no difference between intranasal sprays versus topical antihistamines at controlling ocular allergies. In other words, Flonase worked as well as Livostin or Optivar at treating the itch associated with ocular allergies.

  Ocular allergies may be exacerbated in patients with dry eyes taking oral antihistamines. Consider switching these patients to steroid nasal sprays to control their allergic rhinitis.

Prescription chronic care drugs

• Mast cell stabilizers

  Mast cell stabilizers are not used in the treatment of acute ocular allergies. They work by stabilizing the mast cell membrane by preventing the influx of calcium. This in turn prevents the degranulation of mast cells. All these products have the same mechanism of action and are efficacious.

  Mast cell stabilizers can be used weeks to months without any significant side effects. They are good for those afflicted with allergies at known times or anticipating exposure to known allergens (e.g., every March and April or visiting a home with cats). They can prevent the ocular allergic outbreak all together.

  1. First generation: Approved only for VKC; dosed qid.
     1. Alomide (lodoxamide 0.1%, Alcon)
     2. Crolom (cromolyn sodium 4%)
     3. Opticrom (cromolyn sodium 4%)
  2. Second generation: Tend to be more potent than older members of mast cell stabilizers; can be dosed bid. Remind patients that the drop does not get rid of immediate symptoms. It is wise to start 1 week before allergy season begins with second generation mast cell stabilizers because it takes 1-2 weeks for drops to take full effect. There are 50 million mast cells in the human eye--it takes a while for the drugs to stabilize all those membranes.
     1. Alocril (nedcromil sodium 2%); very expensive
        Has been proven effective in trials up to 21 weeks. It is indicated for the itch of allergic conjunctivitis; works on both early and late phase of allergic conjunctivitis. It has a slight yellow color. Alocril is unique because it is used bid. It can be increased from bid to qid if advanced disease. Allocril inhibits eosinophils, neutrophils, and macrophages. It blocks the release of histamine and the release of leukotrienes (as expected).
     2. Alamast (pemirolast potassium 0.1%)
        Indicated for the itch of allergic conjunctivitis; works on both early and late phase of allergic conjunctivitis. Alamast has been shown to be effective at bid dosing, but loading dose probably needs to be qid.

  Mast cell stabilizers can increase wear times in those with a history of allergic conjunctivitis and contact lens intolerance. In one study, 59 disposable contact lens wearing patients with a history of allergic conjunctivitis and contact lens intolerance were given either artificial tears or Alocril. After 4 weeks, both treatments extended wearing times, but Alocril allowed for a greater increase in wear time than did the artificial tears. This study is a good reminder that contact lens intolerance can be due to low grade allergy problems. The patient does not always have to be experiencing significant allergy problems to have difficulty wearing contact lenses. Mast cell stabilizers can be used safely and comfortably with contact lenses.

Homeopathic formulations

Similasan's Eye Drop #2: Preservative free and contains extracts of honey bee, eyebright, and cevadillas. A small quantity of the allergen is allowed to enter the patient's blood stream, and over time, he or she will develop resistance to it. Only anecdotal evidence exists that the drop actually works. There are no scientific studies that document Silmilasan's efficacy in treating allergic conjunctivitis.

Eyebright and honeybee extract have also been touted to "promote" eye health. In regards to controlling allergic symptoms, however, most individuals are not allergic to eyebright, and honeybee stings do not typically cause allergic conjunctivitis.

Safety profiles of ocular allergy medications

Pregnancy (Category B--Use in pregnant and nursing women only as clearly needed): Alocril

Safe for children:

• Alomide (2 years and above)
• Alocril (3 years and above)
• Alamast (3 years and above)
• Emadine (3 years and above)
• Patanol (3 years and above)
• Zaditor (3 years and above)
• Crolom (4 years and above)
• Optivar (4 years and above)