allergy
Spring is in the Air . . .
And allergic conjunctivitis is in your chair.
BY GLENN S. CORBIN, O.D., Reading, Pa.

The good news is that allergic conjunctivitis isn't life-threatening. The bad news is that many of our patients suffer from acute or chronic symptoms that affect their everyday activities and decrease their quality of life. As primary eyecare providers, we're responsible for diagnosing and treating patients who experience ocular allergy. Recognition of and appropriate management of ocular allergy is paramount to a successful therapeutic practice.

Did you know?

According to the Allergy Report from the American Academy of Allergy, Asthma and Immunology (AAAI), allergic disorders represent the sixth-leading cause of chronic illness in the United States and affects more than 50 million people. A 2003-2004 Gallup poll reveals that 83% have ocular symptoms. Increased absenteeism and reduced productivity because of allergies costs U.S. companies more than $250 million each year. Schools may inadvertently send children home because of conjunctivitis that's allergic (noncontagious) in nature, but mistaken as bacterial.

What are allergies?

Allergies are the immune system's adverse response to what we'd normally consider harmless substances. From airborne particles such as pollen, molds and dust mites to pet dander, foods or medicines, people's bodies can react in a variety of ways including dermatitis, rhinitis and/or conjunctivitis. Often the response is mild, but severe reactions can occur because of exacerbations with greater exposure to the allergen(s). People who have allergies have an inherited genetic tendency to produce IgE, the allergy antibody, to many different substances.

Something's in the air

Typically, airborne particles have the greatest propensity to cause ocular allergy as well as nasal or respiratory symptoms. Ocular signs/symptoms may include hyperemia, serous discharge, itching, tearing and/or chemosis. Because mast cells are abundant in the conjunctiva, histamine is the key player in seasonal or perennial allergic conjunctivitis.

Outdoor allergen VIPs

Pollens and molds are the most prominent outdoor allergens. Each spring, trees and grasses release tiny particles known as pollen, which become airborne. Although their mission is to fertilize parts of other plants, many never reach their targets. Instead, they find their way into human noses and throats and eyes, causing a chain reaction leading to an allergic event.

Probably even more common than pollen allergy is mold allergy. While pollen affects people seasonally, mold affects us every night with little regard to seasons. Pollen is released during the hottest part of the day so that the thermals can carry the pollen far and wide. Mold goes off during the night. (This occurs in a process called "sporulation," as opposed to pollen's "pollenation.") Mold can't tolerate sunlight, so the most efficient mold will sporulate at the darkest time of the night.

It's important to know when your local allergy seasons begin and to monitor pollen counts to better prepare yourself for the arrival of allergy symptoms. Realize that pollen counts can vary depending on time of day, environmental conditions and an individual's level of sensitization.

Is this a good time for you?

Because many patients report for their eye exams when their allergy symptoms are inactive, we must proactively gather histories and seek out signs or symptoms of ocular allergy.

An important rule of thumb in my practice is that if a patient documents a medication, then a corresponding condition must associate with it, even if it's prophylaxis. The large number of patients taking oral anti-histamines is a critical clue to the potential for ocular allergy. Unfortunately, 90% of ocular allergy patients self medicate, taking over-the-counter products that they may not report in their history and may be inadequately treating their symptoms. Often the patients don't realize that we prescribe for this condition and, if inactive at the time of exam, will never mention it to us. Even worse, they may already be taking a prescribed topical medication from their primary care physician, when, in fact, we should have "made the call" first and initiated prescription treatment for our patient. If we better understand the allergic process, we can better diagnose and manage our patients.

Right under our noses

If you consider how we develop a therapeutic practice, it's obvious that we encounter acute onset disease patients who visit us because of signs and/or symptoms that require immediate attention. The rest of our disease-patient encounters are typically those that require our expertise to make the diagnosis, such as glaucoma or "out-of-season" allergic conjunctivitis.

What this boils down to is that we already have thousands of ocular allergy sufferers in our practices who haven't been diagnosed and could really use our help. The significance of monitoring the pollen count in your area and heeding the results of the 2003-2004 Gallup Poll is to increase our awareness of when our patients may be most likely to present with or experience ocular allergy symptoms, be it episodic or chronic.

The big four

We typically classify ocular allergy into four categories:

1. Seasonal/Perennial allergic conjunctivitis (SAC) and (PAC), respectively

2. Giant papillary conjunctivitis (usually contact lens-related)

3. Vernal keratoconjunctivitis (VKC)

4. Atopic keratoconjunctivitis (AKC).

The allergic response in the eye is most often a Type-I hypersensitivity IgE-mediated reaction. The ocular surface becomes sensitized to environmental allergens followed by mast cell degranulation and release of histamine and other preformed mediators. This type of reaction results in the symptoms typically seen in allergic conjunctivitis, either seasonal or perennial, most frequently encountered in optometric practice. It's considered the acute allergic reaction and mast cell degranulation is the principal event. Histamine stimulates blood vessels, nerves and mucus-producing glands, resulting in the characteristic signs and symptoms of allergic conjunctivitis.

Migration of leukocytes into the site of an acute allergic response characterizes late-phase allergic reactions. Although the late-phase response occurs in conjunctival tissue, no clinical symptoms appear associated with this response in the vast majority of patients.

VKC and AKC aren't simple Type-I immediate hypersensitivity diseases. The pathophysiological reactions in these two diseases are more leukocyte dependent, involving both mononuclear and poymorphonuclear leukocytes. Eosinophils in VKC and lymphocytes in AKC conditions take on active roles in these diseases and are responsible for corneal damage such as keratitis, limbal infiltrates and ulcers. These represent potentially sight-threatening ocular allergy conditions that require prompt diagnosis and effective management.

Here's where you come in

Treatment of ocular allergy is similar to that of any allergy, except that topical treatment (vs. oral) is most effective. In fact, the drying effect of oral anti-histamines can exacerbate the allergic event by reducing tear volume and thus lessening the eye's ability to naturally flush out allergens. Patients are unaware of this information and typically "assume" that their oral medication should adequately treat their ocular symptoms. Even if not satisfied that their eyes feel as good as they'd like, they assume that nothing more can be done.

We should familiarize ourselves with topical anti-allergy medications, particularly their mode of actions, indications, side-effect profiles and their relative efficacies. Preferred agents are those that have been proven safe in children and adults, have a broad range of anti-allergy indications, demonstrate little to no risk of side effects and provide a long enough duration of action to allow b.i.d. dosing. Dual mechanism drugs, anti-histamine/mast cell stabilizers such as olopatadine 0.1% (Patanol), allow both immediate relief and long-term prophylaxis for our patients.

A simple plan

A step-wise approach to therapeutic care for any disease makes sense. Make the diagnosis, categorize the severity and start your treatment. Dispense a sample drug accompanied by a written prescription for the patient to fill after he returns for follow up. This implies to your patient that the sample is a prescription drug that he must take according to your directions.

Schedule your patient back in two to three weeks for follow up to assess the efficacy of your treatment. Educate your patients as to avoidance of allergens and preventive care options. Adjunctive therapy, including palliative treatments, such as cool compresses and lubricants, may be appropriate to prescribe. Use your prescription pad to write down patient care instructions to help ensure that your patients are compliant.

Ask the right questions, even if your patient incorrectly fills out his history form and omits allergy-related symptoms. No pun intended, but "out of sight, out of mind" holds true when our allergy sufferers don't consider their "in season" symptoms when filling out a medical history form during an "off season." Be sure to use a provocative history form that encourages patients to tell you how their eyes feel throughout the course of the year.

You've got the power

Treating ocular allergy can prove both satisfying to your patients and rewarding to your practice. The power of prescribing rests in your hands.

References available on request.