estimated 20 percent of the U.S. population experiences allergies -
and this percentage seems to be growing. Some surveys (Gallup Poll
2003-4) suggest that this number may be as high as 50 percent of the
population and that 90 percent of these individuals experience
ocular symptoms as well. Moreover, studies have shown that eye
allergies are under reported.
with these statistics, patients in our practices report significant
negative effects from increased healthcare-related costs due to
decreased productivity and quality of life. In fact, consumers'
out-of-pocket costs and the indirect costs of productivity
reductions and lost workdays have had an economic impact estimated
to be at least $5 billion a year.
this population of allergy sufferers are many of our patients who
wear contact lenses of all types. We, as practitioners, must be
cognizant of our patents' trials and tribulations in attempting to
wear contact lenses in the midst of suffering symptoms of allergic
rhinitis, allergic conjunctivitis and dry eye-related allergies.
Let's examine the effect of this problem on our contact lens wearing
population, which is more than 30 million in the United States
study, allergic rhinitis patients reported being bothered by their
allergy symptoms, both nasal and ocular, on an average of nearly
four days during the week before they were questioned. Each patient
reported experiencing ocular symptoms on at least one day of that
week, and approximately 20 percent reported experiencing ocular
symptoms every day of that same week.
contact lens wearers, these individuals would experience continuous
ocular symptoms during their entire wearing schedule each week and
would eventually either give up on contact lens wear or, at best,
become partial wearers who might wear their lenses only on social
occasions. But even these individuals most likely would not be
comfortable in this situation, and eventually they, too, would
choose to give up on contact lens wear if no long-term solution was
become increasingly evident in clinical practice that there's no one
solution for any contact lens wearer experiencing ocular allergy.
Many contact lens wearers blame the contact lens fit for the
problem. Many blame dryness as the cause, and others realistically
know that the root of their problems lies in the systemic allergic
response and its further effects on their eyes.
Establishing the Goal
practitioners, we have a treatment goal with any allergic patient,
contact lens wearer or otherwise. That goal is an approach that
targets all aspects of the allergic response with optimal efficacy,
immediate onset, extended duration and the utmost comfort and
safety. This may involve a pharmacologic approach, holistic
approach, allergen avoidance approach or an environmental lifestyle
change approach. When the complication of contact lens wear is also
present, further changes may be necessary in contact lens material,
lens type or lens solution to try to enhance wearing comfort.
The Ocular Allergic Mechanism
important to understand the allergic cascade and ocular allergy
mechanism of action when dealing with contact lens patients. Most of
the allergy we deal with as ophthalmic practitioners is of the Type
I hypersensitivity variety mediated by the immunoglobulin IgE. There
are four phases of this complex process: sensitization; mast cell
degranulation; activation, or early phase; and late phase response.
ocular allergy is a specific and narrowly focused form of ocular
inflammatory disease. The primary cell involved is the mast cell, of
which there are some 50 million in the human eye. During allergic
episodes, mast cells move or migrate to the superficial tissue
layers where they are degranulated by immune or mechanical stimuli.
Once degranulated (Figure 1),
histamine, the principal mediator of allergic conjunctivitis,
releases into the blood stream and causes vasodilatation and
erythema, increased vascular permeability (edema) and neural
stimulation (itching - the hallmark of allergy) (Figure
Figure 1. Mast cell degranulation is one
of the complex allergy processes.
Figure 2. Ocular allergy symptoms.
pre-formed mediators are also released during this cascade: tryptase,
chymase and heparin to mention a few. In addition, other newly
formed mediators are also released: prostaglandins, leukotrienes,
cytokines, etc. All of these play a role in the allergic response,
but to reiterate, the principal mediator is still histamine.
allergic patients seasonally (SAC), episodically (EAC) or
perennially (PAC) depending on what allergen affects them. These are
generally acute conditions, but if an individual is affected by more
than one entity, this condition may be present all year. Of the
chronic allergic conditions we see giant papillary conjunctivitis in
contact lens wearers more than we see either vernal
keratoconjunctivitis or atopic keratoconjunctivitis. Patients have
also reported ocular symptoms from unilateral irritation of the
nasal mucosa. In the nasal-ocular reflex (also called the
ocular-nasal reflex), allergens in the nose stimulate inflammatory
mediators, which in turn stimulate the trigeminal ganglion. This
often results in ocular vasodilatation, erythema, plasma leakage and
tearing. In this situation a nasal anti-inflammatory agent may offer
relief of both nasal and ocular symptoms.
the above conditions may occur in contact lens wearers, complicating
what may be an ill-fitting lens, an improper lens material for that
patient or an incorrect contact lens solution for that type of lens
or patient (Figure 3). Our job is
to rule out the obvious and to investigate the not-so obvious to
properly diagnose the condition for each individual patient.
Figure 3. Symptoms of an allergic reaction to a contact lens
The Role of Dry Eye
Complicating this further is the condition of dry eye syndrome,
which practitioners must differentially diagnose before applying any
treatment regimen. It used to be said that if the eye burns, it's
dry eye; if the eye itches, it's allergy; and if the eye has mucus
discharge, it's bacterial until proven otherwise. While this old
adage still may hold some water, the diagnosis is much more
complicated than that because of the various mechanisms of action
described above in the allergic cascade.
differentiating dry eye from true allergy, you need to take some
important steps. First and foremost, good history taking is
paramount. Does the condition the patient describes involve itching
vs. burning or dryness? If so, obviously the diagnosis would be more
simplified and targeted to allergy. However, let's assume that you
had nothing so specific to guide your initial impression. In this
case, what would you do? A complete battery of dry eye tests would
be in order, beginning with biomicroscopic evaluation of the tear
layer for its composition (thickness, debris, meibomian gland oil
and sebaceous secretions) as well as the tear meniscus for its
apparent volume. Obtain a tear break-up time (TBUT) to help assess
the quality of the tears. Next, stain the conjunctiva with
fluorescein dye, use a Wratten filter and evaluate the cornea. Also
evaluate whether the conjunctiva has dry spots or dry areas. Use
lissamine green dye to additionally evaluate staining on the
conjunctiva. Then use a Phenol Red Thread Test (Zone Quick) to
evaluate the amount of fluid present in the conjunctival sac. I
don't recommend a Schirmer analysis because I don't believe in its
level of accuracy or repeatability.
simple procedures will reveal if the patient's complaint truly
results from a dry eye component or whether you can rule that out
and direct your focus to allergy related issues.
A Stepped Approach
make the differential diagnosis, treatment for contact lens patients
may be as simple as cold compresses and ocular lubricants. If this
fails the next method of choice is to prescribe a multi-action eye
drop that at least would stabilize the mast cell wall from further
degranulation and additional release of histamine, along with an
antihistamine to specifically bind with the histamine receptor and
relieve the itch. These multi-action drops are highly prescribed.
The most popular drugs in this category are Patanol (Alcon), Zaditor
(Novartis), Elestat (Inspire Pharmaceuticals) and Optivar (MedPointe).
Alcon has also introduced an ocular allergy eye drop approved for
once-a-day dosing called Pataday.
Tailor Your Treatment
Practitioners must treat every contact lens-wearing patient
individually based upon his working and living environment, lens
type, lens schedule and lens solution. Reduced wearing time may be
necessary until the acute symptoms are alleviated, but patients
remaining in lenses will probably also be on some ocular
pharmaceutical agent as described above.
deciding what pharmaceutical agent to use, you must be aware of your
patient's wearing schedule and how acute the symptoms are so you
don't prescribe an agent that could possibly exacerbate the problem.
Topical ocular anti-allergy medications are generally more effective
than systemic medications are for contact lens wearers. In our
clinical practice, it appears that using these agents helps keep
more patients in lenses during allergic episodes. Having noted that,
it's also important to realize that many of our contact lens
patients are also using systemic anti-allergy medications prescribed
by their physicians as well as intranasal steroids for general
allergic rhinitis symptoms. When this is the case, as it often is, I
wouldn't counsel a patient to stop taking a systemic drug without
first talking with his physician. The physician needs to know that
even non-sedating antihistamines can cause drying, and this may
complicate the treatment plan in the contact lens wearer.
Assessing the Contact Lens
As far as
lens types and lens materials go, we need to assess whether the
current contact lenses meet the intrinsic needs of the patient.
know that GP lens materials vary in Dk values, which will certainly
affect oxygen transmission and ultimately long-term comfort. In the
soft lens arena, we have daily wear lenses that have indications for
allergic patients. We have lenses that have added properties such as
phosphorylcholine to help address dryness and discomfort. We also
have lenses that are aspheric in design and, by virtue of their
added movement, aid with the oxygen pump upon blinking.
have several new silicone hydrogel contact lenses that have higher
Dk values than older soft lenses, which again aids in oxygen
transmission to the cornea. Because these silicone hydrogel lenses
are traditionally lower in water content, lens manufacturers have
incorporated additives to help create softer-feeling lenses or lower
modulus, which may ultimately be more comfortable. Moreover, we now
have contact lens solutions formulated for increased levels of
moisturizing and comfort for longer wearing times.
these newer products have brought with them a level of awareness
that we, as practitioners, didn't previously have. This has
ultimately led to improvements in lens wearing comfort and longer
wearing schedules for our patients, even for those who have ocular
and systemic allergies.
Diagnosis is Key
difficulty in determining what's best for each patient is in the
proper diagnosis of the allergic condition in the first place. Once
diagnosed, the practitioner needs to base the treatment plan upon
the individual lens wearer and his individual desires and wishes.
approach will work for everyone. Much of this may be trial and error
at the outset, but patience and persistence can prevail. You can
attain the desired outcome with the patient once again becoming a
happy contact lens wearer, symptom-free or controlled.
most of us in a primary care setting realize that getting to the
proper end-point may involve increased costs to our patients. Of
course there's a cost-benefit ratio to any treatment regimen, but
for our contact lens patients, who have already spent and continue
to spend lots of money on their lenses and solutions, it's
imperative to remember that they want results.
adding drug therapy for an existing contact lens wearer, I believe
it's efficacious both from a treatment and monetary standpoint to
prescribe the best drug for the patient, no matter what the cost.
The bottom line is that our patients want to have the best effect.
If a patient experiences a positive result from a particular drug
and will ultimately be more comfortable in contact lens wear, he'll
be less concerned about the cost.
Ultimately, what we're trying to provide to our contact lens
patients is an overall improvement in their quality of life. When
allergies begin to interfere with a patient's ability to wear
contact lenses in addition to making him physically miserable, this
quality deteriorates in some cases to what appears to be a point of
critically important that we recognize our patients' symptoms and
not treat these allergic conditions in a cavalier manner. A happy
patient will refer many other patients to us to solve their problems
as well. You can build a handsome practice when keeping this
ultimate goal in mind.