Causes of Eye Allergies

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Do you have red, itchy eyes? You may be suffering from a condition that affects millions of Americans: eye allergies. Eye allergies sometimes cause significant discomfort, often interrupting daily activities with annoying symptoms.

Causes

A person develops eye allergies when the immune system overreacts to an allergen. An allergen is a word for any substance that can cause an allergic reaction. Allergens may be found indoors or outdoors and include things such as grass, tree and weed pollen, dust, and pet dander.

When exposed to these allergens, cells in the eyes release histamines and other chemicals in an effort to protect the eyes. It is this chemical reaction that causes blood vessels inside the eyes to swell, and the eyes to become itchy, red and watery. Allergies can also trigger other problems, such as conjunctivitis (pink eye).

Types of Eye Allergies

Eye allergies are generally categorized into two types: seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC).

  • SAC:
    The most common type of eye allergy; people affected by SAC experience symptoms during certain seasons of the year.
  • PAC:
    These types of eye allergies are usually caused by dust, pet dander or other allergens that are often present year-round.

Symptoms

The following symptoms commonly occur with eye allergies:

  • Itching
  • Redness
  • Tearing
  • Swelling
  • Burning
  • Blurry vision
  • Eye mucous

Although the symptoms of eye allergies can be extremely annoying and uncomfortable, they usually cause no harm to the eyes.

Risk Factors

Allergic eye reactions occur when a person is sensitive to an allergen. Eye allergies often affect the conjunctiva, the clear covering that covers the front part of the eyeball. This clear covering is the same type of material that lines the inside surface of the nose. Because the two areas are so similar, allergens can trigger an allergic response in both areas.

Therefore, people with nasal allergies may also suffer from eye allergies.

Diagnosis

An optometrist or ophthalmologist can usually diagnose eye allergies based on a patient's symptoms. To confirm the diagnosis, the eye doctor may use a slit lamp to examine the front part of the eye. This examination may reveal the presence of conjunctival and eyelid swelling and dilated blood vessels, which would confirm the diagnosis. In some cases, the doctor may use an instrument to scrape the conjunctiva to check for the presence of eosinophils, cells that are present in severe cases of eye allergies.

Treatment

The most effective treatment for eye allergies includes minimizing exposure to the allergens that are triggering the allergic response. This may include staying indoors when pollen counts are high, wearing sunglasses to prevent pollens from entering the eyes, reducing the amount of dust present in the home, and cleaning floors with a damp mop instead of a dry sweeper. Those suffering from eye allergies may also try avoiding irritants such as cigarette smoke, air pollution, and strong odors.

Contact lenses should also be avoided while allergy symptoms are present, as symptoms can cause discomfort with contact lenses.

Medications

Both prescription and over-the-counter (OTC) medications can be beneficial to those suffering from eye allergies. OTC artificial tears, decongestants and antihistamines can be effective in treating short-term symptoms. Artificial tears help flush the allergens out of the eyes. Decongestant eyedrops are available without a prescription to help alleviate eye redness.

Prescription medications are highly effective in relieving symptoms. Antihistamines reduce itching, redness and swelling, usually rather quickly. Mast cell stabilizers may be used to help prevent the release of histamines, thus reducing symptoms

Source:

Eye Health Media Guide. "Allergies", pages 2.8 - 2.11. Alcon, Inc., 2008.

"Allergies of the Eye." University of Michigan Kellogg Eye Center, 2008.

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