Itchy, burning and watery eyes, sneezing and a runny nose? It’s hay fever season again! Allergies to ragweed and other pollens cause millions of Americans discomfort.
Pollens are often the culprits behind allergic eye irritation, but there are other causes too. Allergic reactions to drugs, for example, may cause the eyes to itch and swell.
The eyelids and the conjunctive are the ones easily affected in an allergic reaction. The conjunctiva is a membrane that lines the inside of the eyelids and extends over the front of the white part of the eye (sclera). Inflammation of the conjunctive caused by an allergy is called allergic conjunctivitis.
What is an allergy?
An allergy is the body’s reaction to a substance that it recognizes as “foreign” and wants to get rid of. As such, allergic reactions are an important part of the body’s immune defense system. When you are allergic to something, your body’s defenses react and produce potent chemicals such as histamine. Histamine is primarily responsible for watery, itchy eyes and many other typical allergic symptoms.
It is unclear why some persons develop allergies. About 10 to 20 percent of the population has allergies. Symptoms can start at any age but children and young adults are more vulnerable to allergies.
What causes allergic reactions?
Allergens are the substances that cause allergic reactions. The most common allergens are found in our environment. The eyes undergo frequent allergic reactions due to exposure to the environment. Ocular symptoms can result from an allergen coming into direct contact with the eyelid and/or conjunctive or can result from a larger allergic reaction (e.g., hay fever).
Contact ocular allergies can occur after using eye drop medications or contact lens solutions.
Airborne allergens that may provoke eye symptoms include:
•Tree, grass and weed pollens.
•Animal danders and feathers.
What are the symptoms of allergic conjunctivitis?
The main symptom is itching of the eyes. The individual may experience redness and burning of the eyes as well as excessive tearing. Symptoms generally not associated with allergic conjunctivitis include severe Pam, discharge of pus, and decreased vision.
Allergic conjunctivitis is most commonly a short-term (acute) problem. It may uncommonly be a long-term (chronic) condition.
Acute allergic conjunctivitis occurs with hay fever and other seasonal allergy. It causes sudden, mild to severe swelling of the conjunctive and eyelids. The conjunctive appears pale but with easily visible blood vessels. Itching and burning are prominent symptoms. Tearing also occurs. The person with this type of conjunctivitis almost always has nasal symptoms as well.
Chronic allergic conjunctivitis is nonseasonal, occurring continuously or on and off year-round. It is less common and potentially more severe than the acute type. It is caused by an allergen to which the person is more or less continually exposed (dust, foods, danders, etc.). Unlike the acute type, there is little evidence of inflammation. However, itching and burning are present. Sensitivity to light may be a problem.
This chronic problem is sometimes misdiagnosed as dry eye syndrome or as nonallergic conjunctivitis. Occasionally the symptoms are even considered psychosomatic until the allergen is identified and avoided.
How is allergic conjunctivitis diagnosed?
Usually the diagnosis of allergic conjunctivitis is easily made based on physical examination and the patient’s medical history. In addition to the typical signs and symptoms of allergic conjunctivitis, the patient often has a history of other allergic conditions and/or a family history of allergy.
Tests can be helpful when the diagnosis is uncertain, as may be the case with chronic conjunctivitis. One test involves scraping the conjunctival tissue and staining the tissue sample for eosinophils. Eosinophils are a class of white blood cells that are almost always present in tissue affected by an allergic reaction.
In addition to diagnosing the allergic reaction, it is helpful to identify the substance causing it. An allergist can perform skin testing or sometimes blood tests in an attempt to pinpoint the offending allergen(s).
What treatments help allergic conjunctivitis?
The best relief for any allergy is to eliminate or reduce exposure to the allergen. While avoiding certain drugs or foods may provide a solution, treatment would be more difficult if the offending allergen is as widespread as pollens. In these cases, taking medications to blunt the allergic reaction may be necessary.
In mild cases of allergic conjunctivitis, ocular itching and other symptoms may be tolerable without treatment. If symptoms become troublesome, a cold compress applied to the eyes could afford temporary relief from itching. Some persons with mild to moderate symptoms may obtain relief by using ocular lubricants or medicated drops. A vasoconstrictor is the most commonly used medication. This type of drug shrinks the congested blood vessels in the conjunctive and reduces swelling. These drugs are available as eye drops, and many do not require a doctor’s prescription.
Other medications may be needed for comparatively severe and acute allergic conjunctivitis. Some eye drops combine a vasoconstrictor and an antihistamine. Antihistamines relieve itching and tearing by blocking the action of histamine. When the allergic reaction involves parts other than the eyes, oral antihistamines may be helpful.
Another type of eye drop actually inhibits the release of histamine from one of its main sources in the body, the mast cells. Cromolyn sodium (Opticrom) drops may be used over a long term to reduce the number and severity of acute episodes of conjunctivitis.
Patients with severe allergic conjunctivitis may need to use any or all of the above medications with the addition of corticosteroid drops. Steroids should not be used over a long term as prolonged use may lead to cataracts or glaucoma in some patients.
The goal of therapy is to reduce symptoms to a tolerable level using as little medication as possible.
If medical therapy is not effective, the patient may need to consult an allergist for further treatment.
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