allergy
Welcome To Fall Allergy Season
Help your patients and exercise your prescribing rights by giving your patients the most comprehensive care available for their allergies.
GLENN S. CORBIN, O.D., Reading, Pa.

Autumn has arrived and behold! -- along with last minute battles to reach the Fall Classic, another allergy season is upon us. Ragweed and other allergens accompany this change of season, taking their toll on our patients' respiratory systems. They can play a critical role in evoking allergic conjunctivitis and its accompanying symptoms.

Fight the OTC trend

As primary eyecare practitioners, we must be diligent in diagnosing and treating those who suffer from seasonal or perennial ocular allergy. In the United States, the incidence of allergic rhinitis is 20% to 25%. Consider that 60% of these individuals may have ocular symptoms -- our role is even greater than one might imagine. Decreased productivity can occur from ocular allergies, accounting for lost school and work days. The effect on a person's "quality of life" is not limited by age, gender or visual status.

Additionally, approximately 90% of ocular allergy sufferers use over-the-counter eye drops. These eye drops have many shortcomings, including poor efficacy, short duration of action and a host of adverse effects such as stinging, burning and possibly increased hyperemia.

We need to get busy

Patients are often unaware of available topical prescription treatments that have more convenient dosing regimens, longer and more efficacious effects and less risk for adverse events. What is even worse is that 80% of prescriptions written for these products are by primary care physicians, pediatricians, allergists and ophthalmologists. When we consider that most eye exams are performed by optometrists, we realize that there's much room for improvement in our prescribing habits. Patient retention, referrals, busier schedules and increased income are just a few of the tangibles to be gleaned by uncovering and treating ocular allergy. These tangibles are discussed by Dr. John Rumpakis on page 60.

Here's how it works

We typically classify ocular allergy into the following four categories:

1) Allergic conjunctivitis: Seasonal (SAC) or Perennial (PAC)

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

3) Vernal keratoconjunctivitis

4) Atopic keratoconjunctivitis

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 is seen in garden variety allergic conjunctivitis, either seasonal or perennial. It's considered the acute allergic reaction; mast cell degranulation is the principal event. Histamine stimulates blood vessels, nerves and mucous-producing glands, resulting in the characteristic signs and symptoms of allergic conjunctivitis.

Late phase allergic reactions are characterized by migration of leukocytes into the site of the acute allergic response. Although the late phase response occurs in conjunctival tissue, there does not appear to be any clinical symptoms associated with this response in the vast majority of patients. Vernal and atopic keratoconjunctivitis are not simple Type I immediate hypersensitivity diseases.

The pathophysiological reactions in these two diseases are more leukocyte dependent, involving both mononuclear and polymorphonuclear leukocytes. Eosinophils in vernal and lymphocytes in atopic 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. Therefore, prompt diagnosis and effective management are imperative.

Understanding mast cells

Since not all mast cells are alike, understanding mast cell heterogeneity is an important part of understanding the role of available pharmaceuticals in treating ocular allergy. Mast cells have two phenotypes: Tryptase (T) and Tryptase/Chymase (TC). Tryptase-containing mast cells are present in mucosal tissue such as in the respiratory tract, whereas Tryptase/Chymase containing mast cells are found primarily in connective tissue such as the skin and also the eye. Most importantly for us, different mast cell types react differently to drugs. Thus, information about the direct action of drugs on mast cells from the eye is critical to choosing the most appropriate drugs for our patients.

Antihistamines take action

Research since the 1960s shows that antihistamines have a biphasic effect on cell/biological membranes. Antihistamines cause inhibition of secretion or, in the case of mast cells, degranulation at low concentrations, then they actually stimulate mast cell degranulation and histamine release at higher concentrations. This release of histamine is thought to be due to non-specific cell membrane damage (all cells, including corneal epithelium), possibly from disruption of membrane integrity as the amphipathic antihistamine molecules can readily insert themselves into the membrane. This is of interest to eyecare practitioners because the concentrations of antihistamines applied onto the eye are in the ranges that can disrupt cell membranes.

Stay informed

When we consider treatment options for our patients, we must understand the science of the allergic response as well as the science of the treatments we prescribe. Review the published literature on the various topical ophthalmic drops and use this knowledge of mast cell heterogeneity and biphasic effects of antihistamines to help guide your prescribing. The only currently approved mast cell stabilizer/antihistamine allergy eye drop to address all the signs and symptoms of allergic conjunctivitis is Olopatadine 0.1% (Patanol, Alcon Laboratories Inc.). Olopatadine 0.1% treats TC mast cells (oculo-specific) and does not exhibit a biphasic effect.

Prescribe proactively

Our primary means of identifying the allergy patient is to obtain a detailed medical history. The chances are not so likely that each of the allergic patients in your practice will come in for an eye exam with active signs and symptoms of allergy at that time. This is why you need to ask the right questions. Include questions that are not limited just to the time of the exam, but rather probe symptoms that may occur at any time during the year. For instance, many patients neglect to admit using topical OTC eye allergy drops.

In addition to questioning the use of systemic antihistamines or OTC eye drops, ask about a family history of atopic disease, the occurrence of specific symptoms such as itching (the defining symptom of allergy), redness, tearing or swollen eyes. Also inquire about contact lens discomfort or intolerance during particular situations or times of the year. For example, we see many patients who present during the "off-season" without ocular allergy symptoms, but when queried will admit to "in-season" symptoms. Herein lies the opportunity to proactively present new convenient treatment options to your patient and to issue a written prescription for to start and carry them through the active phase of the allergy season.

This strategy can influence patient retention and satisfaction. Have your patient begin treatment several weeks before symptoms usually begin to offer prophylaxis prior to the allergic cascade. Expand your clinical exam to include lid eversion, looking for palpebral conjunctival changes consistent with ocular allergy. Don't ever underestimate the power of writing a therapeutic prescription for your patient. Make follow-up appointments at that prescribing visit to assess the effectiveness of your treatment and assure patient satisfaction.

Beyond the ocular surface

A study presented at the 2004 Association for Research in Vision and Ophthalmology meeting highlights the importance of treating ocular allergy as a means of effecting allergic rhinitis. Seventy-eight allergic rhinoconjunctivitis sufferers were challenged with a conjunctival allergen at one visit and a nasal allergen at another. The investigators found that introducing an allergen to just the ocular surface induced all the signs and symptoms of allergic rhinitis and allergic conjunctivitis.

Although more investigative work needs to be done, the implication is that by preventing the drainage of ocular surface allergens and conjunctivally released allergic pro-inflammatory mediators, via topical ocular allergy treatment, we may be assisting in the reduction of allergic rhinitis symptoms. It's also possible that topical ocular drops can drain into the nose via the naso-lacrimal duct and supply anti-allergy therapy to the nasal tissue. On follow-up assessment visits, I often hear anecdotal remarks from my patients about the reduced rhinitis symptoms that they experience since they started treatment for ocular allergy.

Don't let your guard down

Optometry has worked very hard to expand our diagnostic and therapeutic capabilities over the years through advanced education and clinical training. A common denominator amongst us all is the ability to prescribe topical eye drops for our allergy patients. Good clinical practices dictate our role in identifying these patients and offering them the most comprehensive up-to-date care available. Remember that ocular allergy is usually ongoing (perennial) or recurrent (seasonal) and requires vigilant monitoring on our part.

The formula is simple: If we take our responsibility seriously, our patients will receive better care and our incomes will rise as a reflection of our practice growth.