Question: Our ophthalmologist evaluated a patient with acute angle-closure glaucoma and performed serial tonometry followed by bilateral pachymetry. Which codes and how many units of each should we report for the multiple tonometry measurements and pachymetry on both eyes? Maine Subscriber Answer: When the ophthalmologist is documenting pressure changes throughout the day or monitoring response to treatment, you can bill for serial tonometry if they check the intraocular pressure (IOP) three or more times over the course of several hours. Report 92100 (Serial tonometry (separate procedure) with multiple measurements of intraocular pressure over an extended time period with interpretation and report, same day (eg, diurnal curve or medical treatment of acute elevation of intraocular pressure)) for that service. You don’t need to report multiple units of this code, since it refers to “multiple measurements.” Three is the magic number: Most Medicare carriers require that the ophthalmologist perform three tests over six or more hours before the service can be considered serial tonometry. Don’t report 92100 just because the ophthalmologist performed tonometry once or twice during an eye exam. Medicare and CPT® both consider tonometry incidental to an intermediate or comprehensive exam for a new or established patient coded to 92002–92014 (Ophthalmological services: medical examination and evaluation …) or an evaluation and management (E/M) service. This is true even if the provider repeats the tonometry. Ophthalmologists also often use pachymetry for glaucoma patients to determine the correlation between corneal thickness and IOP. Submit 76514 (Ophthalmic ultrasound, diagnostic; corneal pachymetry, unilateral or bilateral (determination of corneal thickness)), which is inherently bilateral, so you’ll report it only once whether one or both eyes are tested. Note: Pachymetry performed to assess or monitor glaucoma is usually allowed only once per patient. Check for bundling: There are no National Correct Coding Initiative (NCCI) edits that prevent you from reporting 92100 and 76514 together, so if the patient needs, and the physician performs, both services on the same date, you should bill both codes.