Contrast Sensitivity Testing

Here are the ins and outs of this test that measures functional vision.

By Suzanne L. Corcoran, COE

The highest quality vision does not necessarily correlate to 20/20 on a Snellen chart. A more discerning measure of functional vision is contrast sensitivity testing. New IOLs have rekindled an interest in this diagnostic tool as patients search for better outcomes following cataract and refractive surgery.

Q. What is contrast sensitivity?
Contrast sensitivity refers to the visual system�s ability to distinguish between an object and its background. For example, imagine a black cat on a white, snowy background (high contrast) vs. a white cat on a white, snowy background (low contrast). In all conditions where visual acuity is reduced, contrast sensitivity is reduced as well. However, sometimes contrast sensitivity is reduced more than expected based upon the visual acuity alone. This means that if only visual acuity is tested, the visual disability of the person with relatively reduced contrast sensitivity will be underestimated.

Q. How is it tested and what are the indications?
Contrast sensitivity is tested in two ways: using low-contrast letters or using sine-wave grating with varying spatial frequency. Contrast sensitivity testing measures visual performance over a wide range of sizes and contrasts. The purpose of the test is to assess how well a person functions visually to see everyday objects such as faces and signs.
Contrast sensitivity testing is useful as an auxiliary means of assessing visual difficulties in patients who test well with a traditional Snellen chart. (A Snellen chart employs high contrast � i.e., black letters on a white background). Many people can read the 20/20 line yet still complain of visual difficulties, such as driving at night (i.e., low contrast conditions). This may be due to optical aberrations of the visual system, contact lens problems, ocular pathology, complications related to medications or ocular manifestations of systemic diseases.

Q. What CPT code describes contrast sensitivity testing?
Where contrast sensitivity testing is used to evaluate abnormal vision, it is considered an incidental part of an eye exam or consultation; no separate CPT code describes the test. Do not use 92499 (unlisted ophthalmological service) to unbundle contrast sensitivity testing from the remainder of the office visit unless instructed to do so by a payer.

Q. How can we be paid for performing contrast sensitivity testing?
There are two ways physicians may be paid for this test: as part of a covered service like an eye exam, or as a non-covered service such as screening. Covered services are indicated for pathology or abnormalities, while non-covered services include screening or routine eye care. Non-covered services are billed to the patient.

Use a Notice of Exclusion of Benefits forms (one for Medicare and one for other payers) when the test is for screening purposes. These forms notify the patient that the service is not covered, either by statute or by the insured�s policy, and that the beneficiary is financially responsible.
The Advance Beneficiary Notice (ABN) informs the patient that Medicare coverage is uncertain. For example, an ABN is appropriate when a disease is suspected but not found or when an indication is not covered by the local Medicare policy. It is not used for screening services. OM

Suzanne Corcoran is vice president of Corcoran Consulting Group. She can be reached at (800) 399-6565.