the contact lens exam
Every Contact Lens Exam
Begins With a Case History
BY JENNIFER L. SMYTHE, OD, MS, FAAO, AND PAMELA WONG, OD
What are the key elements of a contact lens exam? We like to tell our students it's as simple as "very fun pocket change" -- a mnemonic device for
vision, fit, physiology and compliance. Throughout the year, savvy clinicians will highlight specific aspects of the contact lens exam, covering a range of topics from over-refracting to wavefront to culturing and lab diagnostics that make assessing these four components easier and more understandable. We'll start at the beginning of the exam with the case history.
Take the Time to Chat
Every exam begins with a case history, which is a valuable tool in contact lens patient management because direct questioning can shed light on each of the four key elements of assessment. Here's how.
How's Your Vision?
Patients can tell you a great deal about their quality of vision that goes beyond high contrast Snellen acuity. (Consider testing low contrast VA also.) A soft toric lens wearer who notices fluctuating vision throughout the day may have unstable lens rotation. A patient who complains of blurry vision late in the day may be experiencing lens dehydration. Patients can also indicate that they are experiencing aberrations from a too small optical zone, residual astigmatism or lens decentration by describing halos around lights, split images or poor night vision.
You can also get an indication of how a patient's lenses fit during a case history. Patients who experience redness late in the day may have tight fitting lenses. Patients who suffer from persistent lens awareness and variable vision may have flat fitting lenses. Poor vision complaints may result from an unsatisfactory lens-to-cornea relationship such as lens vaulting, which can occur with stiffer lens materials or large diameter soft toric lenses. Spectacle blur or the inability to easily switch between contact lenses and eyeglasses could indicate corneal molding or edema.
Subjective complaints of itching, dryness, stinging, burning and grittiness can all suggest a compromised ocular surface. Asking a patient to define the severity of particular symptoms (for example, more itching than dryness) provides clues to help you determine the underlying etiology of the discomfort (possible ocular allergies vs. possible dry eye). Stinging upon lens application may indicate solution incompatibility as opposed to stinging later in the day, which more often results from dryness.
The case history can also reveal if your patients are complying with their lens care and wear schedule. Rather than asking patients, "Do you sleep in your lenses?" ask them, "How often do you sleep with your contact lenses on?" You can reveal patients' true wearing habits by simply rephrasing the question.
Now that many solutions have "no-rub" labeling, remember to ask patients whether they rub their lenses and/or rinse them for the adequate length of time. Quite often you'll discover that they're doing neither.
Ask patients at the yearly visit how many lenses they have at home to determine whether they comply with their replacement schedule. This can help you determine whether you need to change a patient's modality.
Time Well Spent
Do an annual complete review of systems and take the time to talk to your patients at every visit.
Dr. Smythe is an associate professor of optometry at Pacific University and is in private group practice in Beaverton, Oregon. Dr. Wong is the current cornea and contact lens resident at the Pacific University College of
Contact Lens Spectrum, Issue: January 2004