Ultrasound plays an important role in ophthalmology. It's used for a variety of indications, and new uses continue to appear as our understanding of the eye and vision-related disease grows.

Here, we'll discuss new indications for ultrasound, common billing problems related to ultrasound, and legal and regulatory headaches.

Pachymetry and glaucoma

Most payers don't associate pachymetry with glaucoma, but evidence suggests that corneal thickness can affect intraocular pressure (IOP). As a result, pachymetry may increase the accuracy of glaucoma diagnosis.

When tonometry is used to measure IOP, the instrument is calibrated assuming a standard corneal thickness of 520 microns. However, a study published by Emara (in the Journal of Cataract and Refractive Surgery, 1998), found the standard deviation of corneal thickness to be �37 microns.

At the same time, the Rotterdam Study indicates that for every 10 microns variance in corneal thickness, IOP varies 0.2 mm Hg. And a study published by Ehlers (Acta Ophthalmologica, 1975) suggests that the IOP variance related to corneal thickness may be even greater than this.

Consequently, the IOP of a patient with unusually thick corneas, say 620 microns, could be overstated by 2.0 mm Hg or more. This error could be clinically significant. Likewise, unusually thin corneas may yield understated IOPs, even when real pathology is present.

In either case, corneal pachymetry could be helpful -- especially in those patients who show signs of glaucoma, but without the expected corresponding IOP measurements.

Pachymetry is accomplished using an A-mode ultrasonic measurement procedure. This is a form of ophthalmic biometry, but without intraocular lens power calculation. For that reason, when you submit a claim for this procedure, 76516 is the most appropriate Current Procedural Terminology (CPT) code to use. (Note: We're aware that the Medicare carrier for Iowa used 76599 to describe pachymetry, although this is an unlisted procedure.)

Because most payers wouldn't link pachymetry with glaucoma diagnoses (coded 365xx), some caution is advisable. Notify patients, prior to testing, of their financial responsibility in the event that the third-party payer doesn't cover pachymetry for this indication. Also, write a letter of appeal to explain the medical justification for the pachymetry.

Concurrent A and B scans

Many doctors are confused about how to bill for concurrent A and B scans. This is largely because of the way code 76512 is described in CPT: "Ophthalmic ultrasound, echography, diagnostic, contact B-scan (with or without simultaneous A-scan)."

Fortunately, Medicare provides some clarification in its Correct Coding Initiative (CCI). 76512 isn't bundled with 76519, so you can perform these procedures together as long as suitable indications are present.

How can you tell whether to bill A and B scans discretely or as one service? Two key factors:

�        Are they serving a single purpose or different purposes?

�        Are they performed simultaneously or separately?

The following examples should help to clarify the difference.

�        Case 1: A patient presents with a hypermature cataract that doesn't allow you to view the retina. Prior to scheduling cataract surgery, you perform an A-scan to measure the axial length and calculate the necessary IOL power, and a B-scan to assess the retina's condition.
Although you performed both ultrasound tests during the same office visit, you didn't do them at the same time, and you used them for different purposes. Therefore, you should submit separate claims for each procedure.

�        Case 2: A patient presents for evaluation of a subretinal lesion. You perform a two-dimensional B-scan to collect information about the topographic nature of the lesion (its position and shape). A simultaneous A-scan yields information regarding the size of the lesion.
In this case, the A-scan was performed at the same time as the B-scan, for the purpose of enhancing the results of the B-scan. Therefore, the two scans should be billed as a single procedure.

Unilateral or bilateral?

In 1994, Medicare published new instructions concerning claims for A-scan biometry with IOL calculation (76519). Prior to that time, ophthalmologists billed for this procedure on a per- eye basis and received equal payment for each test. The revised instructions defined A-scan biometry in a novel way. Unlike other diagnostic tests -- which are either unilateral or bilateral -- this test was defined as being both.

Medicare defines the technical component (measurement) as bilateral, and the professional component (interpretation) as unilateral. Special modifiers are amended to the CPT code to make this distinction: -TC for the technical component, and -26 for the professional component. In some areas, local modifiers may be required as well (e.g., -ZP in New York).

So where's the problem? The claim for the first A-scan is no longer the same as the claim for the second one, and the payments are different, too.

Confusion reigns

Consider the following: A patient with bilateral cataracts opts for surgery in the right eye. When your technician performs the A-scan, he measures both eyes, even though only the measurement of the right eye is necessary for the planned surgery. Your office should submit a claim for 76519-TC as well as 76519-26RT. (Or, you can simply use 76519-RT to obtain the same outcome.)

Later, when you plan surgery for the left eye, you can use the original measurement to perform the IOL calculation. You should submit this on the claim as 76519-26LT. However, reimbursement for the second claim is only 40% of the value of the first claim. (Local carriers may publish slightly different instructions concerning modifier usage, but the result is the same: reduced payment for the second claim.)

This strange regulation has confused physicians and payers alike. Two common problems have resulted:

�        When the -TC and -26 modifiers are omitted from claims, some Medicare carriers have continued to pay claims under the old rules, long after the new rules were implemented. This has resulted in overpayments. Later, when the overpayments are uncovered, physicians have been obligated to make refunds to Medicare.

�        Physicians sometimes forget to bill the subsequent A-scan interpretation, especially if they believe that A-scans are now bilateral -- an easy mistake to make.

This method of billing and reimbursing A-scans is unique to Medicare. Other third-party payers don't segregate the technical and professional components in this manner, and payment is the same for each A-scan biometry.

Other issues

Other issues involving ultrasound that have caused confusion include:

�        Compensation and designated health services. Under the Stark law, ultrasound A and B scans are considered designated health services. This affects how compensation can be made to members of your practice. Physician compensation can't be based on revenue generated by designated health services. In practices where physicians are paid based on productivity, revenue earned from designated health services such as ultrasounds must be excluded from the compensation calculation.

�        Ordering tests. Reimbursement for diagnostic tests is reserved for the ordering physician who plans to use the results to diagnose and treat the patient. If you don't intend to use the test results to care for the patient, don't order them.
For example, a general ophthalmologist who observes a patient with vitreous hemorrhage secondary to diabetic retinopathy and refers the patient to a retina specialist shouldn't order or perform a B-scan. The scan is likely to be repeated by the retina specialist.

�        Supervision of testing. On Oct. 31, 1997, Medicare published a new rule concerning physician supervision of diagnostic tests: All ophthalmic tests should be performed under direct supervision. This means that the physician must be available in the office suite or building to advise or assist during the procedure. However, the physician's presence is not required in the exam room during the test.
This new rule was rescinded January 28, 1998, at which point carriers were instructed to revert to their own policies. But until HCFA publishes a final rule, you should make arrangements to ensure that your office follows current policy.

The future looks bright

Despite regulatory limitations, ultrasound has tremendous utility in ophthalmology. If you choose to use it in your practice, make sure you code correctly -- both to avoid legal pitfalls, and to ensure that you get the full reimbursement Medicare allows.

Kevin Corcoran is president of Corcoran Consulting Group. Mary Pat Johnson is a senior consultant with the same firm, located in San Bernardino, Calif. You can reach them at (800) 399-6565, or via e-mail at: www.corcoranccg.com.