What Is an Allergy of the Eye?
Allergies of the eye, like all allergies, are overreactions of the immune system to foreign substances, which might otherwise be harmless. If you don’t have allergies, the immune response that occurs following exposure to an allergen is controlled and produces few, if any, symptoms. If you do have allergies, activation of the immune response results in the release of inappropriate, high quantities of chemical mediators—the most common is histamine. These mediators are responsible for the symptoms of allergic reactions. The different types of allergies affecting the eye are: atopic allergies (vernal keratoconjunctivitis, atopic keratoconjunctivitis, and hay fever conjunctivitis); medication reactions; and contact lens-related allergies.
Different Types of Allergies
- Vernal keratoconjunctivitis is a seasonally-recurring conjunctivitis that generally occurs in children and young adults and affects the peripheral cornea.
- Atopic keratoconjunctivitis is not seasonal but generally occurs in older patients who have had a history of atopic eczematoid dermatitis. It can cause more extensive corneal and conjunctival scarring if untreated.
- Hay fever conjunctivitis, also known as seasonal allergic conjunctivitis, is a sudden intense response to an (usually) airborne allergen. It tends to be short-lived and episodic.
- Medication Reactions
- IgE mediated (anaphylactoid) is a sudden, intense reaction which often includes chemosis (conjunctival swelling) and an urticarial response (intense itching). Common offenders include topical penicillin, bacitracin, sulfacetamide, and anesthetics.
- Toxic papillary reactions are very common and result in a chronic red eye. These can occur any time after one week of medication use and are due to some antibiotic and antiviral drops, as well as certain preservatives.
- Allergic contact reactions are slower and more gradual in onset than the above two. They are caused by many topical medications and are easily treated by discontinuing use of the medication.
- Contact Lens-Related Allergies
- Contact allergic conjunctivitis occurs when the contact lenses themselves, or the proteins from tears that bind to the surface of the lens, irritate the conjunctiva, resulting in redness, itching, mucous discharge, and lens discomfort. A more severe form, known as giant papillary conjunctivitis, causes large swelling of the mucous membranes of the upper lid and ultimately may result in the inability to wear contact lenses.
- Swelling or puffiness of the eyes
- Mucous discharge
- Contact lens discomfort
- Foreign body sensation
The symptoms described above may not necessarily mean that you have allergies of the eye. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam.
The cause of allergic conjunctivitis is dependent on the type (see above)
The risk factors are specific to the type of allergic conjunctivitis (see above)
Tests and Diagnosis
Most types of allergic conjunctivitis can be diagnosed by a careful clinical examination and history
Treatment and Drugs
- Atopic Allergies
Using cool compresses and artificial tears is often helpful. Topical vasoconstrictors and antihistamines are useful to counteract the histamine-induced leakiness and dilation of blood vessels. Many of these are available as over-the-counter medications. Mast cell stabilizers (cromolyn sodium, lodoxamide) can be used in seasonal cases and are most effective if taken before or soon after the onset of symptoms. These drugs limit the body's sensitivity to an allergen, resulting in a less severe immune response. Topical steroids may be used in severe cases.
- Medication Reactions
Discontinuing the medication that caused the reaction typically clears allergy symptoms. Topical vasoconstrictors and antihistamines may provide relief; artificial tears may help remove any remaining medication and lubricate the corneal surface if irritated.
- Contact Lens Allergies
Decreasing lens wear time, insuring proper cleaning of lenses, and perhaps changing the cleaning regimen may improve this condition. In addition, recognizing early symptoms is essential in limiting this problem. For example, you should monitor your wearing time and remove your contact lenses when you notice that your eyes are red and irritation. If these measures are not helpful or if there is already moderate to severe disease, your doctor may prescribe mast cell stabilizers and a short course of mild steroids to help "put out the fire" and limit the body's response. If still not helpful, consider changing the lens type. A period of weeks to months without any lens wear is often helpful in controlling this allergy.
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Reviewed by Jill E. Bixler, M.D.