contact
lens practice pearls
Uncovering
Causes of Contact Lens Associated "Dryness"
BY
THOMAS G. QUINN, OD, MS, FAAO
The
symptom of dryness during lens wear is perhaps the most common patient complaint.
But are they suffering from true dryness? Here are a few great pretenders and
how to identify them.
Mechanical
Irritation
Lenses that move a bit too much or have a less than ideal
edge may irritate the eye so subtly that we often see few signs to tip us off. In
some cases the superior tarsal plate may develop papillary changes in response to
excessive rubbing during the blink. These changes will be more localized than what
you'll observe in response to allergy (Figure 1). Be particularly suspicious of
mechanical issues if the patient is wearing a higher-modulus lens material.
Hypoxia
Consider hypoxia-induced "dryness" if the patient is wearing a
low-Dk/t lens. Besides looking for the obvious corneal signs of neovascularization,
striae and microcysts, also look for a steady increase in myopia over time (myopic
creep). Refitting these patients into a higher-oxygen material lens will provide
relief.
Poor Surface Condition
When assessing lens fit, note the lens surface condition. An oily
surface may result from use of lotions or handsoaps containing moisturizers or perfumes.
Often reviewing proper hygiene habits can resolve this dryness complaint. We recommend
that all patients rub, particularly those wearing silicone hydrogels, regardless
of which system they use.
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Figure
1. Mechanical papillary changes.
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Solution
Sensitivity
If lens fit looks good, the surface is clean and the patient is
already wearing a lens of high oxygen transmissibility, consider the possibility
of dryness symptoms induced by solution sensitivity. This irritation may result
from solution incompatibility with the patient or with the lens material. The interesting
paradox about this condition is that some patients will be symptomatic but show
no slit lamp signs while others may show diffuse staining without comfort complaints.
The key point here is to recognize that even though no physical changes may be observed,
switching patients complaining of dryness into a hydrogen peroxide-based care system
or a daily disposable lens will often resolve the problem.
True Dryness
Of course, some complaining of contact lens-associated dryness
will have a true dry eye. Signs to tip you off include a thin tear prism, lissamine
green staining, a rapid tear break-up time and low tear production measurements.
Explore systemic medications as a possible cause for low tear
production. Ophthalmic medications such as Restasis (Allergan) may help. Another
approach is to refit the patient into a "moisture retaining" material.
In the presence of poor tear quality, warm compresses and lid
scrubs can help relieve symptoms. Oral agents such as doxycycline or minocycline
may help emulsify the lipid contents of the lid glands. Tablets high in omega-3
oils may also provide relief.
Be a Detective
Discomfort, often in the form of dryness, is the leading cause
of lens dropout. When managing a patient with this complaint, ask questions and
perform a detailed slit lamp examination of the lens, eye and eyelid. This will
reveal the true cause of irritation.
Dr. Quinn is in group practice
in Athens, Ohio, is a diplomate of the Cornea and Contact Lens Section of the American
Academy of Optometry and advisor to the GP Lens Institute.
Contact Lens Spectrum, Issue: September 2006