Article Date: 4/1/2001

coding q & a
Coding Q & A
Insights into accurate coding from a nationally known expert.

We're considering the addition of a scanning laser for nerve fiber analysis. How is this test billed?

Answer: In January 1999, Medicare approved nerve fiber analysis as a procedure for the diagnosis and follow-up of glaucoma. The CPT code is 92135 and it applies to both glaucoma and retinal evaluations using Heidelberg Retinal Topography (HRT), Humphrey Optical Coherence Tomography (OCT) and Laser Diagnostic Technology (GDx).

Points to remember

The procedure is unilateral, so each eye is billed separately. Remember, this means you must use the modifiers RT (right) or LT (left). The 2001 Medicare allowable for this procedure is $56.89. Because this test has two components (technical and professional) you must submit a separate interpretation and report in the medical record for proper documentation and compliance purposes.


TABLE I: Diagnoses covered by scanning laser glaucoma test


362.85 retinal nerve fiber bundle defects

364.22 glaucomatocyclitic crisis

364.53 pigmentary iris degeneration

364.73 goniosynechiae

364.74 pupillary membranes

364.77 recession of the angle

365.00-365.9 glaucomas

368.40-368.45 visual field defects

377.90 unspecified disorder of the optic nerve or pathways

377.00-377.04 papilledema

How insurers view the procedure

Some carriers have placed frequency edits on the procedure. Most agree the test is valuable in a glaucoma suspect's or early glaucoma patient's evaluation and treatment.

Medicare defines glaucoma suspect as any one of the following:

Nerve fiber analysis is also helpful for patients with moderate damage. In mild to moderate disease, the scanning laser glaucoma test (SLGT) is payable once or twice per year, not with a visual field. In advanced glaucoma, most carriers view visual fields as more valuable and rarely pay for scanning laser tests.

Diagnoses covered by SLGT appear at left. As you'll note, this test is used for other diseases, as well.

If you deem this test medically necessary for a condition not listed in the table, inform the patient that Medicare won't cover testing. Have him sign a waiver accepting financial responsibility. Use the GA modifier, which lets Medicare know that you've had the patient sign a waiver.

Some private insurance companies will deny reimbursement, claiming the procedure "experimental and investigational." If you're denied for this reason, resubmit the claim with a letter of medical necessity. Reference FDA's official notification stating that the device was issued 510K clearance (#K941705) on 7/18/94, effectively removing it from the experimental and investigational device list.

This technological breakthrough is invaluable in diagnosing and monitoring glaucoma patients or those at risk. It's another source that can give us more confidence about a decision to treat or not to treat.

Our options are increasing

Manufacturers and distributors continue to find creative ways of delivering this technology to us at a more reasonable cost. Recently, manufacturers have developed portable models, lease programs and mobile services. These options will increase the use of these instruments and improve quality of care. Adding this service to your practice will also increase your net revenues and profit. So try it for the health of your patients and your practice.

Dr. McGreal is center director of the Missouri Eye Institute, a VisionAmerica Co-Management Center in St. Louis. He also lectures on clinical and practice management topics.

If you have a coding question you'd like answered, send it to Terri Goshko, c/o Optometric Management, 1300 Virginia Drive, Suite 400, Ft. Washington, PA 19034. E-mail

Optometric Management, Issue: April 2001