92100 CPT Code: Complete Billing and Coding Guide for Serial Tonometry

“Can I bill CPT 92100 separately if intraocular pressure was measured multiple times during a routine exam?” This is one of the most frequently asked questions by billing compliance teams and payer medical reviewers. According to CMS Medicare Part B use statistics, approximately 72,000 claims for CPT code 92100 were filed in 2023, with an anticipated denial rate of more than 18%. The majority of rejections are caused by documentation mistakes, missing modifiers, or incorrect billing in conjunction with general ophthalmological services or E/M codes.

CPT 92100 is used for serial tonometry, which means measuring intraocular pressure (IOP) multiple times on the same day to identify pressure fluctuations. It is frequently used for glaucoma monitoring and identifying aberrant diurnal pressure oscillations. Billing this code correctly necessitates following stringent clinical, scheduling, and documentation standards, many of which are commonly misinterpreted or inconsistently applied.

This guide offers practical, expert-level explanations for optometrists, ophthalmologists, billing experts, and practice managers. It discusses modifier usage, paperwork requirements, Medicare and MAC coverage guidelines, and preventing denials. Each part is meant to assist clinicians in appropriately reporting 92100 and remaining compliant with current reimbursement guidelines.

What Is the 92100 CPT Code?

This section covers an official definition and clinical application of the 92100 CPT Code. It explains what the method entails and when it should be reported.

CPT 92100 Definition and Use

Serial tonometry is identified by CPT code 92100. This approach entails multiple intraocular pressure (IOP) measurements conducted at various intervals on the same day. The idea is to detect variations in ocular pressure that may not be apparent during a single reading.

The procedure is coded as:

92100: Serial tonometry (separate procedure), with multiple measurements of intraocular pressure (IOP) over a single day

The 92100 CPT Code falls under ophthalmology CPT codes, especially special ophthalmological services and procedures. It is mostly diagnostic.

This code should not be used for single IOP measurements. These are covered in general ophthalmology or E/M services and do not require separate reporting.

Clinical Application

Serial tonometry is commonly used in the diagnosis of glaucoma, particularly when pressure variations are predicted throughout the day. It helps in detecting pressure spikes that may occur outside of normal visit times.

92100 is suitable for the following cases:

Monitor patients with probable diurnal IOP fluctuation.

Evaluate the reaction to pressure-lowering medicines.

Evaluating IOP variations in acute glaucoma patients.

Who Can Bill the 92100 CPT Code?

Not all providers and clinics are eligible to report CPT code 92100. This section discusses who can charge for serial tonometry and what conditions must be met under Medicare and commercial payer standards.

Eligible Providers

The 92100 CPT Code is commonly billed by:

Licensed Optometrists

Board-certified ophthalmologists.

Hospital outpatient departments

Eye care centers with adequate supervision and documentation.

Independent Diagnostic Testing Facilities (IDTFs), if requirements are satisfied.

The provider must confirm that the test is clinically required and done using certified equipment. Documentation must include serial IOP values obtained at different times on the same day.

Medicare and Scope-of-Practice Rules

Although Medicare does not have a national coverage determination (NCD) for serial tonometry, billing is regulated by local MAC guidelines. In 2025, Novitas and First Coast declared CPT 92100 is only receivable when billed by the ordering provider’s specialty, optometry or ophthalmology, as part of eye care services.

MACs also enforce Medicare’s NCCI revisions and global surgical guidelines. Because CPT 92100 is a “separate procedure,” providers can simply report it if all components of the code description are fulfilled.

Billing for comprehensive eye exams (CPT 92002-92014) requires detailed documentation that identifies the services and time of IOP readings.

If billed by an IDTF, the supervising physician must fulfill credentialing and licensing criteria.

Reimbursement is based on the correct usage of modifier -26 (professional) and -TC (technical) when components are divided.

Documentation Requirements for Serial Tonometry (92100 CPT Code)

To report CPT 92100, correct documentation is required. This section describes what information should be included in the medical record to avoid audits and rejections.

Required Documentation Elements

To report the 92100 CPT Code, the following information must be carefully documented:

A clinical purpose for serial tonometry (e.g., monitoring diurnal IOP change or assessing glaucoma)

The precise timing of each intraocular pressure (IOP) measurement.

At least three different IOP measurements were conducted over a single day.

Documentation indicating that the readings were separated and not taken sequentially

The provider’s evaluation of the readings, including a description of results and clinical significance.

Audit and Compliance Considerations

Serial tonometry is frequently subject to post-payment evaluation. To prevent recoupment:

Provide a clear justification for the test (for example, pressure spikes or glaucoma development).

Confirm scheduled intervals between IOP readings; CMS expects clinically valid separation.

Ensure that the provider’s remark contains meaning, not just numbers.

Document if the test was conducted within or outside of the usual ophthalmology service.

Modifier Use with 92100 CPT Code

Modifiers help to explain how and where serial tonometry was done. This section describes which modifiers are eligible for invoicing the 92100 CPT Code and how they affect reimbursement.

Common Modifiers for CPT 92100

Using the right modifier ensures accurate claim processing. The following is a list of common modifiers used with CPT 92100.

Modifier	Description	When to Use
-26	Professional Component	When only the physician’s interpretation is billed, not the technical service.
-TC	Technical Component	When billing for the technical portion (equipment use) without interpretation.
-50	Bilateral Procedure	When the test is performed on both eyes during the same session.
-RT	Right Eye	When tonometry is performed on the right eye only.
-LT	Left Eye	When tonometry is performed on the left eye only.
-59	Distinct Procedural Service	When 92100 is performed on the same day as another service, it must be unbundled.
-76	Repeat Procedure by Same Provider	When the test is repeated on the same day by the same provider.
-77	Repeat Procedure by Different Provider	When the test is repeated on the same day by a different provider.

CPT 92100 Reimbursement Guidelines

This section explains how Medicare and commercial payers manage reimbursement for the 92100 CPT code. It also identifies usual rejection causes and explains how to prevent them.

Commercial Payer Rules

Commercial insurers use similar criteria, although they might have more difficult frequency limitations or pre-authorization requirements. For example:

Evolve Vision reimburses serial tonometry once a year, unless pressure Changes or treatment resistance is proven.

Some payers are interested in clinical records that show pressure fluctuations between assessments to prove usefulness.

Modifier usage and separation from normal tests are frequently examined during claims review.

Denial Triggers

The most prevalent reasons why CPT 92100 claims are refused include:

There is no clinical basis for undertaking serial tonometry.

Only one or two IOP measurements were reported.

There is no provider interpretation in the medical record.

Incorrect or missing modifiers (for example, -50, -26, or -TC).

Billed using an E/M or eye test code, with no apparent separation of services.

Conclusion

To accurately report the 92100 CPT code, precise documentation and payer-specific billing criteria must be followed. Providers must validate clinical necessity, use appropriate modifiers, and separate this treatment from normal checks. Reimbursement is dependent on required medical need, time-based testing intervals, and accurate interpretation. Medicare and private insurance are still attentively reviewing these claims. Missing or limited records often result in denials or post-payment demands. Consistent attention to coding guidelines protects both revenue and compliance.