ALLERGIES
Allergies and Contact Lenses
Bone up on allergies with a review of allergic response and management strategies for contact lens-wearing patients.
By John Mark Jackson, OD, MS

Spring is just around the corner, and with it comes the dreaded allergy season for many patients. For contact lens wearers, this can be a particularly troublesome time of year. As the pollen, ragweed and other allergens raise their ugly heads, your patients will be coming to your office for good solutions for their problems. Fortunately, we can combat this problem in the northern hemisphere.

Allergies can affect contact lens wearers in three ways: environmental allergies causing increased lens problems, allergies to deposits on the lenses and sensitivities to care solutions. First, let's review the allergic response and causes of patient symptoms.

Figure 1. Papillary conjunctivitis of the upper lid, often seen in allergies.

Review of the Allergic Response

Allergy is a Type I hypersensitivity reaction to an environmental stimulus, or an antigen. An antigen could be pollen, ragweed, animal dander or a myriad of other agents to which patients can be sensitive. Allergy represents an exaggerated physiological response to one of these foreign substances. The allergic reaction is mediated through immunoglobulin type E (IgE). The hypersensitivity causes a "chain reaction" in the body. After exposure to an antigen, a complex series of events leads to the release of preformed mediators from mast cells. The most important of these mediators is histamine. Release of histamine from mast cells results in histamine attachment to special receptors in nearby tissues. The result of this cascade is vasodilation, edema of tissues and stimulation of nerve endings causing itching in the eye. Itching and red, puffy eyes are the classic symptoms of allergic conjunctivitis. Papillary conjunctivitis is also a common finding in ocular allergy.

Allergies are treated medically through a variety of mechanisms. Antihistamines are the most common types of drugs used for allergies. They work by binding to histamine receptors on tissues, blocking histamine from binding, and thus preventing the vascular and itch response. They are most useful in the acute phase of allergy. Mast cell stabilizers (MCSs) function by preventing release of histamine from mast cells. As they can take several weeks to reach full potency, they are better for treating chronic allergy conditions. The newest form of allergy drugs is combinations of antihistamines and MCSs and are very popular with clinicians, as they are able to curb acute symptoms while providing long-term relief. Topical NSAIDs can be used for allergies as well; they raise the sensory threshold of nerve endings, decreasing the sensation of itching. Topical ocular steroids are also used to treat allergies, but less commonly than other medications. Of course, the old standby of cold compresses can bring relief to allergy sufferers as well.

	Figure 2. Make sure your differential diagnosis is correct, and injection is not from another cause.

Environmental Allergies and Contact Lenses

The most common environmental allergy the contact lens clinician must combat is seasonal allergic conjunctivitis (SAC). Approximately 10 to 15 percent of the U.S. population suffers from ocular symptoms of SAC. The incidence varies throughout the year depending on type of allergen and the season. For example, tree pollen levels tend to be highest in winter and early spring; grass pollen levels have spring and summer high points; and ragweed is worst in late spring through early fall.

Symptoms of SAC include the typical itchy, watery eyes associated with allergy. Signs include conjunctival hyperemia, edema and a papillary reaction that tends to favor the lower palpebral conjunctiva. Mucous discharge is also a common finding. There may also be conjunctival staining, especially nasally, associated with eye rubbing to relieve itching.

Another less common type of allergy is chronic atopy. It is estimated that atopic eye disease occurs in less than 1 percent of allergy suffers. Rather than having the on-again, off-again nature of SAC, chronic atopy often continues year-round. Sufferers of chronic atopy often don't experience the itching associated with SAC; they may note scratchy, irritated eyes instead. Signs to look for include eyelid skin that is crenated with fine cracks and folds and thickened and scaly to the touch. A history of multiple allergies and asthma is common.

Contact lens wearers with allergies are often symptomatic and may need to discontinue lens wear during the allergy seasons. Hydrogel contact lenses pose a particular problem, as antigens will bind to the lens surfaces over time, increasing the antigen load presented to the immune system. Decreasing lens wearing time is an important first step in relieving allergy symptoms. Changing to a more frequent replacement schedule will also benefit these patients; when lenses are replaced often, less antigen builds up.

Obviously, the most beneficial replacement schedule is a daily disposable modality (CIBA Focus Dailies are FDA approved for reducing symptoms of SAC in contact lens wearers). This is not always practical for patients, and some prescriptions (toric lenses, for example) are not available in a daily disposable modality. Patients can compromise by wearing daily disposables during the symptomatic periods rather than full-time, and patients with low astigmatism can briefly change to a spherical daily disposable lens. Patients not wearing daily disposables can improve the cleaning regimen by adding an extra-strength daily cleaner such as MiraFlow (CIBA), or an enzyme such as SupraClens (Alcon).

Medical management of these patients requires the common medication categories described above. For SAC, the combination medications, such as Patanol (Alcon), Zaditor (Novartis), and Optivar (Bausch & Lomb) are particularly useful. Topical NSAIDs such as Acular (Allergan) can be useful, but the combination drugs are probably more effective. Alrex (Bausch & Lomb), a site-specific topical steroid, is FDA approved for ocular allergy and is especially useful in SAC.

Use caution when topical medications are instilled with contact lenses. None of these medications are approved for use with contact lenses. Strictly speaking, patients should use their drops about 10 minutes prior to lens insertion and should remove lenses prior to drop instillation as well. Practically speaking, some experts report that use of the combination drugs with disposable lenses poses no significant problem, but conventional lenses should definitely be removed prior to drop instillation.

One final word of caution: patients with dry eye can also report itching as a primary symptom, making allergy diagnosis more complicated. Be sure to rule out dry eye by assessing tear break-up time, tear volume and meibomian gland function prior to diagnosing ocular allergy. Of course, there's no reason the two can't co-exist, making patient management even more challenging.

Allergic Reaction to Lenses and Lens Deposits

While environmental allergens can cause great difficulty for contact lens wearers, often the lenses themselves are to blame for allergy symptoms. Soiled and deposited lens surfaces are responsible for the common clinical finding of GPC (giant papillary conjunctivitis), also called CLPC (contact lens papillary conjunctivitis), which more accurately describes the causative agent. The signs and symptoms of CLPC are caused by a combination of allergy to the lens deposits and to mechanical irritation provided by the deposited lens surface. In soft lens wear, the inflammatory component seems to be a greater factor, leading to a widespread involvement of the entire upper tarsal conjunctiva. In RGP wear, mechanical irritation appears to be the primary reason for CLPC to occur, involving the conjunctiva near the lid margin where the lens edge rubs against the lid. If this is the suspected cause, a modification of the lens edge is indicated. Pushing the edge apex further back may alleviate the problem.

In mild cases of CLPC, the primary symptom is a mild itching upon lens removal and possibly mucous discharge. Because the eye feels better with the lens in initially, the patient may continue to wear the lens for symptom relief, exacerbating the condition. As the condition progresses, the itching becomes more pronounced, and mucous discharge becomes more copious. The hallmark clinical sign is upper tarsal conjunctival papillary reaction, often quite large in the advanced stages, and hyperemia of the tarsal plate. In CLPC, the apices of the papillae often have a whitish appearance distinguishing it from environmental allergies. The white areas may represent fibrotic changes in response to mechanical irritation.

Fortunately, with the advent of frequent replacement lenses, the incidence of CLPC has decreased dramatically. It stands to reason that if lens deposits are the main cause of the condition, then having clean lenses is the solution to the problem. If patients were compliant with our care recommendations, frequent replacement would not be necessary. Frequent lens change appears to be the only reasonable course of action for prevention of CLPC.

Treatment of CLPC begins with a temporary cessation of lens wear. Often this is all that is needed, and the inflammation and symptoms will usually decrease over the course of several weeks. If time does not decrease the severity of the condition, medical management is indicated (of course, some clinicians may prefer to use medications at the outset). Initially, many clinicians today will treat CLPC with combination drugs like Patanol (Alcon), Optivar (Bausch & Lomb) or Zaditor (Novartis), or an antihistamine such as Emadine (Alcon) or Livostin (CIBA). Mast cell stabilizers such as Alamst (Santen), Alocril (Allergan) or Alomide (Alcon) are quite useful for preventing the condition from recurring as well. Another option for CLPC is Lotemax (Bausch & Lomb), a site-specific steroid approved for GPC.

Once the condition has resolved to a clinically-acceptable level, a change in lens wearing schedule or material is in order, as well as reminding patients about the necessity of proper lens care. Patients not already in a frequent replacement plan should be changed to one, and those already on this schedule should try a daily disposable lens. As the lens is changed daily, it is unlikely that the patient will wear it long enough to deposit and cause a recurrence. It is certainly an option to change the patient to an RGP lens, as these materials are far more deposit resistant than hydrogel materials. Some patients are never able to return to successful, comfortable lens wear after suffering from CLPC. You must educate your patients early on about this potential complication of lens wear, and that early intervention may allow them to return to successful lens wear.

Contact Lens Solution Sensitivity

In the early days of soft lens wear, reactions to lens solutions were common. Commonly-used preservatives such as thimerosal and chlorhexidine were well known to cause sensitivities in many patients. Modern lens solutions appear to be mostly free of problems for the majority of patients, but some will still be sensitive to even the most gentle preservatives or other ingredients. It is important to educate patients on the need to stay with the care system you prescribe for them to avoid potential reactions.

Symptoms of lens solution sensitivity include burning or stinging on lens insertion and ocular discomfort. Signs include a diffuse conjunctival hyperemia and a diffuse punctate keratitis. A careful history is an important part of the diagnostic process: has the patient switched solutions lately? Does the burning decline fairly rapidly after lens insertion? If so, and the signs mentioned are present, solution sensitivity is the likely cause of the problem.

When you suspect that solution sensitivity is the cause of patient symptoms, a change of solutions is in order. Be cautious about switching a patient from one multi-purpose solution (MPS) to another, as many of them contain preservatives in the same chemical family. A better choice may be a switch to a care system that is preservative free for the storage step of care. For instance, you may wish to have the patient use QuickCare (CIBA), which disinfects with the Starter solution (the cleaning step) and is followed by a soak in the Finishing Solution (a saline solution preserved by trace amounts of hydrogen peroxide). Another option would be to switch them to a peroxide-based system such as AOSept (CIBA) or Ultracare (Allergan). As the peroxide is neutralized, it converts to preservative-free saline, thus preventing preservative buildup in the lens.

Another alternative is switching to daily disposable lenses. The patient's need for lens solutions will be minimized in this case, and the patient gets the extra benefit of new lenses each day. Daily disposables are an excellent answer for a variety of contact lens problems related to allergies.

However, my clinical impression is that some patients appear to have sensitivities to RGP solutions containing chlorhexidine. If this is the case, changing solutions may help. Switching to Unique pH (Alcon) with Polyquad preservative may help in this case. I have also found success with both the Optimum (Lobob) and Claris (Menicon) care systems. These systems use benzyl alcohol as the preservative, and must be rinsed from the lens prior to insertion. These systems can be hard to obtain in many parts of the country, but they can work very well for patients with sensitivities to other RGP solutions.

Conclusion

Today's contact lens wearers benefit from our arsenal of therapeutic agents to treat ocular allergies. By recognizing signs and symptoms of ocular allergies, you can help patients overcome their discomfort and lens wearing difficulties. Properly educating patients on the potential complications of overwearing their lenses or switching care systems is key to keeping them happy and healthy contact lens wearers.

Dr. Jackson is a faculty member at the Southern College of Optometry in Memphis, TN. He is currently studying the effects of overnight orthokeratology.