This article is more than 5 years old. Information may no longer be current.
Fine-tune your allergy diagnostic skills: ask the right questions, profile patients
Click Here to Manage Email Alerts
| |
Considering that an estimated 50 million people in the United States suffer from allergies, chances are great that your patients have ocular allergy. Because most people have seasonal fluctuations in symptomatology, they may not be experiencing signs and symptoms at the time of their visit to the optometrist. This may be the case even with perennial sensitivities, such as dust mites, household molds and animal dander, because symptoms are in direct relation to exposure.
Optometrists can identify these patients simply by asking the right questions. With a brief, but well thought out medical and medication history keyed to specific queries, clinicians can be assured that they proactively identify ocular allergy patients and, consequently, provide them with the guidance and therapy they need.
Allergy and medication history
The great majority of ocular allergy sufferers will visit the optometrist for an annual check-up, demonstrate no signs or symptoms of allergy and even perhaps forget all about it if it is an off-season period. It is essential that the optometrist prompt the patient with questions such as these:
Do your parents or other family members have allergies or a history of allergy?
We know that allergy sensitivity is a genetically transmitted disorder, particularly associated with the mother’s genotype. An allergic mother has a greater than 45% chance of having an allergic child.
Do you have any known allergies or a history of allergy?
Obviously, if the patient has already been to an allergist and has definite diagnostic proof of sensitivities in other tissue sites such as rhinitis, asthma or childhood eczema, he or she is more likely to also experience ocular allergies at some time. Nevertheless, we also know that it is quite possible to have an allergic sensitivity only in the eye, and not in any other tissue. In these cases, the patient is rarely first seen by an allergist.
Do you ever have episodes of intense itching, along with varying degrees of tearing, redness and swelling, seemingly related to specific activities, such as playing with a cat or dog, cleaning out the cellar, mowing the lawn, working in the garden or hiking in open fields or woods in the spring or fall?
When the patient is being seen out of season, it is very helpful to remind him or her of the many occasions when an allergic reaction might develop. While the association with an animal or with repetitive activities such as mowing the lawn is easily remembered, the sporadic incident after a spring hike may not come to mind without some prompting, even if the reaction was severe.
Do you ever use eye drops for itching or redness?
Often, a patient may be self-treating allergies with topical decongestants that only relieve conjunctival redness. These over-the-counter preparations are not approved for the treatment of allergy and do not relieve itching. Other combination OTC products contain both a whitener (usually an alpha-adrenergic agonist such as naphazoline or tetrahydrozoline) and an H1 histamine antagonist. These products usually contain first-generation compounds that are quite limited in activity, both in duration of action and specificity of effect.
Do you use oral antihistamines at any time of year?
Many allergy sufferers may routinely take oral antihistamines and hope that they also work for their eye symptoms. Because ocular allergy is known to be better treated locally and topically, it is important to educate these patients on how to best treat their ocular allergic symptomatology.
What does ocular allergy look like?
 |  |  |  |
| Vernal keratoconjunctivitis: VKC is a severe inflammatory disease that usually recurs seasonally. It is characterized by intense itching, tearing, mucus secretion and photophobia. | |||
Let’s begin with the more straightforward but rare case of the patient who is experiencing signs and symptoms of ocular allergy at the time of the visit. What does ocular allergy look like? Signs include conjunctival hyperemia with excessive tearing, giving the eye a shiny appearance, as opposed to the dry irritated eye with conjunctival redness that is often seen with dry eye conditions. Conjunctival swelling (chemosis) is sometimes present, more so if the patient has been rubbing his or her eyes. Lid swelling and even closure is also sometimes present, particularly if the allergic reaction has been occurring for some time.
The hallmark symptom is itching. This waxes and wanes depending on the level of allergic exposure. Patients are usually aware of a sudden onset of intense itching followed by cycles of itching thereafter. If a patient is already cognizant of his or her allergy sensitivity, he or she can usually pinpoint the onset of itching to exposure to the offending agent. Because itching is known to occur rather quickly after exposure, often the patient has an initial sensation of intense itching, particularly if the exposure was an isolated and discrete episode, which is followed by the more enduring signs of redness and swelling.
Differential diagnosis
In patients who use OTC eye drops for vague symptomatology, a differential diagnosis is necessary. The presence of intense and chronic itching associated with any corneal involvement points to graver forms of ocular allergy than seasonal or perennial allergic conjunctivitis, such as vernal or atopic keratoconjunctivitis (VKC or AKC). These chronic inflammatory diseases warrant close attention and important pharmacological therapy.
Although not a true form of allergy, giant papillary conjunctivitis (GPC) is often grouped with allergic conditions when discussing differential diagnosis. GPC is often seen by optometrists in their contact lens patients. If the patient assures you that he or she has itching, flipping the upper lids is a necessary step in the differential diagnosis of allergic conjunctivitis from VKC, AKC or GPC, all of which are characterized by papillae on the upper tarsal surface.
Symptoms such as burning, foreign body sensation and irritation — with a notable lack of itching — often point toward a dry eye condition rather than allergy. An evaluation of the tear film and meniscus and the presence of fluorescein staining would confirm dry eye, as keratitis is not associated with allergic conjunctivitis. This diagnosis is confirmed when patients report that these symptoms occur during certain activities, such as reading or watching television, when blink rate decreases, or in certain climactic conditions, such as air conditioning or hot air ventilation.
 |  | ||
| Atopic keratoconjunctivitis: This condition indicates severe ocular allergic disease and typically involves the lids or other non-ocular structures. AKC is usually perennial, but it can worsen in winter months, often accompanied by atopic dermatitis. | |||
If these same dry eye symptoms are associated with inflamed, red lid margins, blepharitis may be the cause. Because the etiology of this disease is a dysfunctional lipid layer of the tear film and not a deficiency in the aqueous layer, as is the case in many forms of dry eye, therapy does not consist only of tear substitutes. Frequent washes with massage along the lid margin using diluted baby shampoo are recommended and can actually result in dramatic improvements in blepharitic conditions.
Pathogenesis of ocular allergy
Seasonal and perennial allergic conjunctivitis can be defined as a series of acute allergen challenges to the eye with greatly varying frequency (that is, acute, seasonal and perennial pertaining to the frequency of these attacks). Mast-cell degranulation and histamine release are responsible for the signs and symptoms observed. Late phase-related eosinophil activation is not involved at a clinically relevant level, because toxic corneal effects and neutrophil infiltration are not manifested in this disease.
Histamine is the archetypal mediator involved in ocular reactions, although mast-cell degranulation also results in the release of tryptase and platelet-activating factor. Prostaglandin and leukotriene synthesis is activated via the arachidonic acid cascade. PGD2 appears to be the principal prostaglandin in immediate allergic reactions, such as those that occur in seasonal ocular allergy.
|
|
Treatment options
Very simply, local topical treatment of ocular allergy is the most effective and safe. Newer antihistamine molecules, such as levocabastine and emedastine, are far more potent and long acting, inhibiting itching for 6 to 12 hours. Olopatadine, ketotifen and azelastine are thought to be dual-action drugs, with antihistamine and mast-cell stabilizing activity combined. These medications are approved only for treatment of itching, with the exception of olopatadine, which is approved for all signs and symptoms including redness, chemosis and lid swelling.
Also note that because discomfort due to allergy can be a primary cause of contact lens failure or dissatisfaction, a long-acting, dual-action agent taken before lens insertion could allow this group of patients to remain more comfortable in contact lenses, as has been shown in clinical study.
Proactively identifying allergic patients in your optometric practice will allow you to educate them about receiving the best treatment. Profiling patients also identifies who is self-medicating without a proper diagnosis.
While it may not be allergy season the day of the visit, it is important to diagnose allergy even in the off-season, preparing patients to successfully manage the allergy season when it does arrive.
For Your Information:References:
- Terry Chin, OD, practices at Andover Eye Associates and is an associate professor at the New England College of Optometry. Dr. Chin can be reached at 138 Haverhill St., Andover, MA 01810; (978) 475-0705; fax: (978) 475-0008. Dr. Chin has no direct financial interest in the products mentioned in this article and is not a paid consultant for any companies mentioned.
- Abelson MB. The importance of treating ocular allergy. Refractive Eyecare for Ophthalmologists. Ethis Communications. Feb. 2001.
- Abelson MB, Sloan J, Gomes PJ. Novel treatments and targets. In: Allergic Diseases of the Eye. Philadelphia: WB Saunders Company. 2001:244-250.
- Bonini S, Lambiase A, Bonini S. Genetic and environmental factors in ocular allergy. In: Allergic Diseases of the Eye. Philadelphia: WB Saunders Company. 2001:1-12.
- Brodsky M. et. al. Evaluation of comfort using olopatadine hydrochloride ophthalmic solution in the treatment of allergic conjunctivitis in contact lens matters compared to placebo using the conjunctival allergen challenge model. Eye Contact Lens. 2003:Apr. 29(2):113-116.