Monitoring Disease Treatment with Contrast Sensitivity
The test is an excellent way to confirm efficacy.
BY DAVID EVANS, PH.D., M.B.A.

Efficient management of disease patients is an important component of daily practice operations.

Some patient visits have specific testing reimbursement and provide relatively straightforward management, while most visits provide only minimal financial support. For example, tests used to monitor disease patients over time, such as visual field testing, are reimbursed and provide a financial benefit for specific visits (typically two per year). But a 1-month follow-up after application of treatment has no specific testing reimbursement. This type of patient interaction provides the biggest challenge for financial effectiveness of patient management within the practice.

It's become difficult to choose the proper treatment for diseased eyes, and then to determine if the treatment is effective. Many practitioners have the experience of treating a patient, and hearing: "I can see better," only to wonder if the patient has had a placebo affect or if a treatment is really working. Or the practitioner may wonder: "How low is low enough?" for the IOP therapy in glaucoma patients.

Monitoring treatment in these patients provides a practice management challenge. Indeed, many patients with early disease have the same acuity before and after treatment, and the retina appears equally unchanged. For glaucoma, field sensitivity is relatively insensitive to short-term changes in glaucoma with treatment. Quick measurement tools that can provide objective indications of the effects of treatment and that aid in communicating with the patient and his or her loved ones can be great practice-efficiency tools.

While thought of primarily as a tool for cataract or refractive surgery evaluation, contrast sensitivity has great benefit as a tool for disease management. In this article, I'll describe how you can use this test to aid in patient evaluation, education and compliance.

Use it in Treating Glaucoma

Researchers in the United States and Europe discovered about 10 years ago that contrast sensitivity improves in glaucoma patients following the initiation of treatment. You can use this measurement to aid in managing your glaucoma patients and in determining if treatment is effective.

An upward shift of 0.3 log units -- or two contrast sensitivity levels on most commercially available contrast tests -- indicates that the treatment has benefited the patient. This type of evaluation is particularly useful in patients who have normal IOP before initial treatment, or when a patient is provided an adjunctive therapy or switched to a stronger medication. The improvement in contrast sensitivity provides a short-term verification of the benefit of treatment. The change in contrast sensitivity typically occurs within 30 to 45 days and remains elevated during the course of treatment.

If contrast sensitivity falls at a later visit, then compliance becomes a question, or perhaps a different medication is needed. Quite often, a glaucoma patient is noncompliant, but then remembers the doctor's appointment and starts taking the eye drops again the day before the visit. When the patient is examined, the IOP appears normal. But in these cases, contrast sensitivity remains depressed or has fallen from the last visit. The patient can then be more specifically questioned about compliance.

Reduction or improvement in contrast sensitivity from visit to visit can be a powerful means to educate patients on the importance of routinely applying the medication. Because glaucoma is painless, patients often perceive little benefit from the medication. However, when the patient and his or her loved ones are shown an improvement in contrast sensitivity with treatment, the power of the medication -- and of your treatment decisions -- become apparent. The test results provide an excellent method to evaluate treatment and to communicate the results to patients. When your techs become comfortable with the testing and its overall value as both an evaluative and educational tool, you've created an important practice efficiency.

Monitoring AMD Treatment

Until about 10 years ago, ophthalmologists had few viable treatments for macular degeneration, other than laser treatments for patients with neovascularization. Now photodynamic therapy is available for advanced disease and nutritional therapy is widely used for patients with early or moderate disease.

Contrast sensitivity is a required test for FDA clinical trials associated with photodynamic therapy as a way to evaluate the efficacy of treatment. General ophthalmologists who treat macular degeneration with vitamin therapy can also take advantage of the practice efficiencies related to contrast sensitivity in tracking this type of treatment. Studies suggest that contrast sensitivity is reduced in patients with early macular degeneration, even when the patient retains excellent acuity. When these patients are placed on nutritional supplements, the patients often indicate that they can see better though there's no measurable change in acuity. But contrast sensitivity often shows dramatic improvements in these patients.

As in patients with glaucoma, these improvements are of a magnitude of 0.3 log units of contrast sensitivity or higher. The improvements provide direct and objective measurements for the clinician to evaluate the treatment, and aid greatly in communicating with patients. For ophthalmologists who put patients on nutritional supplements, contrast sensitivity testing provides a superior way to manage the interaction with these patients.

Testing Routinely

Glenn Pomerance, M.D., of Chattanooga, Tenn., has been using contrast sensitivity testing (VectorVision CSV-1000) to aid in glaucoma and macular degeneration management since the early 1990s. He's placed contrast sensitivity instruments in every room and tests each patient on each visit. The techs use the contrast sensitivity results to educate patients as to any changes in vision with treatment, increasing patient satisfaction levels and providing an efficient avenue for the doctor to better communicate with the patients.

Dr. Pomerance also uses contrast sensitivity to monitor cataract, and clouding of the posterior capsule after surgery. While many doctors test contrast sensitivity only before cataract or YAG surgery to document the need for surgery, he also tests after surgery to show the tremendous improvement provided by the treatment. And finally, Dr. Pomerance uses contrast sensitivity testing to aid in the choice of therapeutic agents, and in monitoring the effectiveness of medication therapy.

"I've found that testing contrast sensitivity on each visit has benefited patient communication, leading to more efficient management of the patient visits," says Dr. Pomerance. "This is particularly useful for showing the improvements with treatment in glaucoma, macular degeneration and cataract patients."

Finally, it's important to keep in mind that various disease states may affect contrast sensitivity differently.

A cataract has a much greater affect on contrast sensitivity then glaucoma or macular degeneration. If a patient has multiple disease states, as is often the case in the older population, the visual results may offset. The patients who provide the best results in regard to monitoring macular degeneration and glaucoma are those with clear media (or pseudophakia) and who have relatively good acuity.

Dr. Evans is a consultant faculty member at the University of Alabama Birmingham. He has performed research in visual function since 1978 and has published many scientific articles and book chapters. He's a well-known speaker at U.S. and European ophthalmology meetings, and has served as an expert witness in a variety of cases. He also serves on the FDA ANSI subcommittee for vision standards. He received a Ph.D. in Ocular Physiology from Indiana University, a Masters in Engineering and an M.B.A. from Wright State University, and a B.S. in Engineering from the U.S. Air Force Academy. Dr. Evans has a financial interest in the VectorVision CSV-1000 contrast-testing instrument.