Allergic conjunctivitis is a common eye condition that affects millions of Americans, causing eye irritation and chronic discomfort. The condition is triggered by airborne allergens, such as pollen, mold, dust or pet dander. In patients with allergies, contact with such airborne substances results in inflammation of the conjunctiva, the clear layer of tissue lining the eyelids and covering the white of the eye.
Causes of Allergic Conjunctivitis
In patients who suffer from allergic conjunctivitis, histamine is released when the offending substance is present, causing the blood vessels in the conjunctiva to inflame and swell. Allergic conjunctivitis, like other allergic reactions, tends to run in families.
Different individuals have allergies to different triggers; one of the most common triggers of allergic conjunctivitis is pollen from grasses, ragweed and various trees. Levels of pollen are likely to be higher on hot, dry, windy days than on rainy days when pollen is washed away. Individual patients, however, may also be allergic to mold, present in damp, cool surroundings. Patients may also be allergic to animal dander, which is sometimes species-specific. A patient may react to cat or horse dander, for example, and not to the dander of dogs.
Symptoms of Allergic Conjunctivitis
Allergic conjunctivitis usually has a rapid onset. Symptoms may be seasonal and usually include at least several of the following:
- Intense itching or burning of the eyes
- Puffy eyelids
- Excessive tearing
- Stringy eye discharge
- Redness from dilated blood vessels in the white of the eye
Allergic conjunctivitis may or may not be accompanied by other allergic symptoms, such as sneezing, runny nose or scratchy throat.
Diagnosis of Allergic Conjunctivitis
Allergic conjunctivitis is diagnosed by a medical consultation, a physical examination of the eyes, and, possibly, skin or blood tests. The allergist looks for:
- Eosinophils, white blood cells indicative of inflammation
- Papillary conjunctivitis (small, raised bumps on the inside of the eyelids)
- Positive reaction to skin test for suspected allergens
For most patients, once diagnosed, allergic conjunctivitis can be well-managed. Patients suffering from the condition should be careful not to rub the eyes too hard because they risk scratching their corneas.
Treatment of Allergic Conjunctivitis
Treatment for allergic conjunctivitis can range from simple and conservative treatment methods to medical intervention if necessary.
Most patients, once their condition is diagnosed, can keep their allergic eye symptoms under control by removing contact lenses, avoiding eye makeup, washing the hands before touching the eyes, never sharing eye drops or anything else that goes into the eyes, and self-administering:
- Lubricating eye drops
- Cool compresses to their eyes
- Over-the-counter oral antihistamines
- Over-the-counter antihistamine eye drops
While oral antihistamines can be very helpful in alleviating the symptoms of allergic conjunctivitis, they may dry the eyes, making them more susceptible to irritation. Sometimes, using both lubricating eye drops and oral antihistamines works well.
When simple home care methods of treatment are not sufficient to solve the overall problem, or during a particularly severe episode of allergic conjunctivitis, the doctor may prescribe:
- Steroid eye drops
- Ocular mast cell stabilizers
- Systemic mast cell stabilizers
Mast cells are a type of white blood cells that release histamine, resulting in an allergic reaction. By using medications that control mast cell production of histamine, either topically or systemically, an allergic reaction is mitigated.
The simplest and most effective treatment of allergic conjunctivitis is to avoid the allergens, but, of course, this is not always possible.
Complications of Treatment
Although allergic conjunctivitis itself is not dangerous, certain medications used to treat the condition may cause damage to the eyes. Ocular decongestants, for example, while they lessen redness by constricting small blood vessels in the eye, are not recommended for long-term use because they may worsen the condition over time. Ocular steroids must be used only under medical supervision since they can elevate eye pressure, damaging vision. Ocular steroids can also increase the risk of cataracts.