Allergy is More Than the Itch

Find the root cause with thorough investigation and testing.

By Whitney Hauser, OD

Doctors use the principle of cause and effect every day. The causal relationship is instrumental for organizing data to arrive at a proper diagnosis. Inexperienced practitioners, however, may try to make up for a lack of clinical experience by relying on “flow chart” medicine. Even seasoned doctors may inquire about a “cookbook” approach to treat a particular condition. Things are rarely that simple, and trying to make a patient’s signs and symptoms fit into all the right boxes—rather than searching for the right boxes to fit the patient’s signs and symptoms—can lead to mismanagement.

Take the itchy eye. To many eye care providers, itch equals allergy. End of story. Perhaps the itch reported, however, is just the tip of the iceberg. Or perhaps it is not an iceberg at all. Ocular pruritus is one of the most common symptoms reported by patients. Although frequently related to atopy, itchy eyes can also be caused by dry eye disease (DED), Demodex infestation, contact lens-related conjunctivitis, giant papillary conjunctivitis, contact dermatoblepharitis, and other entities.1

With cause-and-effect medical practice, patients reporting itch leave offices armed with antihistamines, mast cell stabilizers, and steroids because, after all, itch equals allergy. The same patients return 1 or 2 weeks later with unresolved complaints, or, worse still, they do not return at all.

A THOROUGH HISTORY

Physicians have one chance to make a first impression and an accurate diagnosis. Making the right call does not require excessive chair time, but it does require attention to detail. A strong case history is essential to getting the investigation heading in the right direction.

Where Does it Itch?

Patients who complain of itch directly at the lid margin often have waxy, cylindrical dandruff at the base of the lashes. This is easily identified at the slit lamp, and epilation and microscopy can definitively determine if the eight-legged ectoparasites known as Demodex are the culprits.2 Treating Demodex with an allergy medication will be ineffective. Microscopy provides powerful evidence to patients, reinforces the doctor’s diagnosis, and drives compliance.

Do You Have Other Atopic or Allergic Conditions?

Atopic keratoconjunctivitis, although uncommon, can be vision threatening. Unlike many other allergic conditions, it can cause cicatrizing conjunctivitis and progressive scarring and vascularization of the cornea. Identifying concomitant conditions such as eczema and asthma is crucial because they occur frequently (95% and 87% of the time, respectively) in those with atopic keratoconjunctivitis.3 Careful evaluation of the adnexa may reveal an atopic dermatologic response that may require treatment as well.

Do You Wear Contact Lenses?

Contact lenses cause a variety of pruritic complaints with origins ranging from giant papillary conjunctivitis to solution sensitivities. Some lens-related symptoms can be effectively treated with allergy remedies. However, quelling the symptoms without addressing the root of the problem will leave the patient in an endless cycle of steroids and antihistamines that never provide resolution. There are risks associated with long-term topical steroid use, and these patients may be unnecessarily exposed to the dangers of steroid response, glaucoma development, and early cataract formation.

IS DED INVOLVED?

Patients with allergic conjunctivitis commonly present with itchy, watery eyes. Closer examination at the slit lamp often shows papillae, conjunctival chemosis, and hyperemia. However, allergic conjunctivitis may occur with coincidental signs of ocular surface disease such as superficial punctate keratitis and decreased tear prism.

DED affects between 10% and 15% of all Americans, but individuals with allergy may be at greater risk for dry eye than the general population.4 Many over-the-counter allergy relievers contribute to drying of the ocular surface. Classic oral antihistamines such as diphenhydramine and chlorpheniramine, along with second-generation versions such as loratadine, can exacerbate DED. Decongestants carry similar complications. Even ophthalmic allergy drops prescribed by doctors may cause dry eye symptoms due to preservatives and frequency of administration. Concentration of allergens in the tear film may be higher in the low tear volume of DED patients. Additionally, insufficient volume can alter the eye’s ability to wash away offending agents.5 Measurement of tear prism height and volume can prove to be valuable diagnostic tests.

SYSTEMIC INVOLVEMENT

Complete and accurate diagnosis of allergy may require venturing away from the eye and turning to the body’s system-wide response to allergens. Allergy skin testing is now available for use by eye care providers. Testing kits such as those manufactured by Doctor’s Allergy Formula (recently acquired by Bausch + Lomb) can determine with certainty whether specific environmental factors are triggering the patient’s allergic conjunctivitis. Once this is established, avoidance of offending agents can be practiced and more targeted treatments prescribed.

CONCLUSION

If a doctor sticks to a basic cookbook approach to allergy management, many patients will continue to experience symptoms without relief. Judicious use of testing can narrow the diagnosis and better focus the treatment. With minimal investment in time or equipment, doctors can mix up the right ingredients to satisfy patients. Then, both patient and practice can benefit from the recipe. n

1. Kuryan J, Channa P, Chuck R. The itchy eye: diagnosis, management of ocular pruritis. EyeNet Magazine. February 2010.

2. Gutierrez M. Demodex infestation requires immediate, aggressive treatment by doctor, patient. Primary Care Optometry News. June 2011.

3. Chang-Godinich A. Atopic keratoconjunctivitis. Medscape. March 17, 2015. http://emedicine.medscape.com/article/1194480-overview. Accessed February 11, 2016.

4. Dry Eye Syndrome PPP. http://www.aao.org/preferred-practice-pattern/dry-eye-syndrome-ppp--2013. Accessed February 16, 2016.

5. Hamrah P, Dana R. Allergic conjunctivitis: management. UpToDate. January 2016. http://www.uptodate.com/contents/allergic-conjunctivitis-management. Accessed February 11, 2016.

Whitney Hauser, OD
• Clinical development consultant, TearWell Advanced Dry Eye Treatment Center
• Founder, Signal Ophthalmic Consulting
• Assistant professor at Southern College of Optometry, Memphis
• (901) 229-2137; whauser@signalophthalmic.com
• Financial interest: none acknowledged