Summary & Overview
CPT 0198T: Tonometer Measurement of Intraocular Pressure with Ocular Blood Flow Interpretation
CPT code 0198T covers a diagnostic procedure in which a provider measures intraocular pressure using a tonometer, relates those measurements to ocular blood flow, interprets the results, and issues a report. This combined physiologic measurement and interpretation is clinically relevant for identifying and managing glaucoma and other conditions that affect optic nerve perfusion. Nationally, such services inform clinical decision-making about pressure- and perfusion-related risk factors for progressive vision loss.
Key payers covered in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the service represented by the code, the typical clinical settings in which it is performed, and the major considerations payers assess when covering diagnostic ophthalmic services. The publication summarizes coverage context, common billing modifiers, and places the code within outpatient ophthalmology service lines.
This resource provides clinicians, coders, and policy analysts with the clinical description and billing context for CPT code 0198T, plus guidance on where the service is typically delivered. Data not available in the input is noted where applicable. The focus is on concise, actionable information about the code’s clinical purpose, typical site of service, and the principal payers relevant to national coverage discussions.
Billing Code Overview
CPT code 0198T describes a diagnostic service in which the provider measures intraocular pressure with a tonometer and correlates those measurements with ocular blood flow. The provider interprets the ocular blood flow values and completes a diagnostic report summarizing the findings. This service has clinical value for patients with glaucoma and other optic neuropathies where intraocular pressure and ocular perfusion are relevant.
Service type: Diagnostic measurement and interpretation of intraocular pressure and ocular blood flow
Typical site of service: Ophthalmology clinic or outpatient eye care facility
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient with a history of primary open-angle glaucoma presents for evaluation of disease progression and risk assessment. The ophthalmologist performs measurement of intraocular pressure (IOP) using a tonometer and concurrently assesses ocular blood flow parameters (for example, using Doppler or color flow imaging linked to ocular perfusion measurements). The provider integrates the IOP values with ocular blood flow data, interprets the combined results in the context of the patient's glaucoma status, documents findings, and completes a structured report summarizing IOP readings, ocular perfusion metrics, comparison to prior studies, and clinical interpretation relevant to glaucoma management. Typical workflow steps include patient intake and consent, pretest visual acuity and history, tonometry measurement, ocular blood flow acquisition, provider review and interpretation, report generation, and communication of results to the referring ophthalmologist or the patient for follow-up management.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier | Standard reporting when no modifier applies |
22 | Increased procedural services | Use when the procedure requires substantially greater services than usual (unusual complexity or time) |
23 | Unusual anesthesia | Use if unusual anesthesia is required for the procedure |
51 | Multiple procedures | Use when multiple procedures are billed on the same day and payer requires modifier for secondary procedures |
52 | Reduced services | Use when the service provided is partially reduced or not completed as originally planned |
53 | Discontinued procedure | Use when the procedure is started but discontinued due to extenuating circumstances |
62 | Two surgeons | Use when two surgeons of distinct specialties perform the procedure together |
80 | Assistant surgeon | Use when an assistant surgeon is required and documented |
82 | Assistant surgeon (when a qualified resident is unavailable) | Use for an assistant when a qualified resident is not available and documentation supports the need |
AD | Advanced beneficiary notice-related (payer-specific) | Use when billing requires a payer-specific modifier to indicate beneficiary responsibility |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 207P00000X | Ophthalmology | Primary specialty performing glaucoma-related diagnostic testing and interpretation |
| 2080P0001X | Optometry | May perform tonometry and ocular blood flow testing in clinic settings where scope permits |
| 207K00000X | Ophthalmic Plastic & Reconstructive Surgery | Rarely involved; may be related when ocular adnexa affects testing |
| 207L00000X | Retina/Vitreous | May perform related ocular blood flow assessments when retinal perfusion is a concern |
| 207X00000X | Comprehensive Ophthalmology | Providers who perform diagnostic testing and interpretation for glaucoma care |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
H40.11X0 | Primary open-angle glaucoma, mild stage, unspecified eye | Primary diagnosis for which IOP and ocular blood flow assessment is indicated to monitor disease and progression risk |
H40.11X1 | Primary open-angle glaucoma, mild stage, right eye | Laterality-specific code used when testing and interpretation are for the right eye |
H40.11X2 | Primary open-angle glaucoma, mild stage, left eye | Laterality-specific code used when testing and interpretation are for the left eye |
H40.12X0 | Primary open-angle glaucoma, moderate stage, unspecified eye | Used when the patient has moderate glaucoma requiring ongoing IOP and perfusion assessment |
H40.20X0 | Unspecified glaucoma suspect, unspecified eye | Used when ocular hypertension or suspicion of glaucoma prompts IOP and ocular blood flow evaluation |
H40.29X0 | Other primary glaucoma, unspecified eye | Used for glaucoma variants where perfusion and IOP correlation is clinically relevant |
H54.8 | Other visual impairment | Used when reduced vision prompts comprehensive evaluation including IOP and ocular blood flow testing |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
92100 | Serial tonometry with multiple measurements of intraocular pressure | Basic tonometry used for IOP measurement; may be performed before or in addition to the ocular blood flow assessment |
92133 | Scanning computerized ophthalmic diagnostic imaging, posterior segment, unilateral or bilateral; optic nerve | Imaging used to evaluate optic nerve structure in glaucoma patients and often included in the diagnostic workup alongside IOP and blood flow assessment |
92250 | Fundus photography with interpretation and report | Document retinal and optic nerve appearance; supports correlation between blood flow findings and retinal pathology |
92136 | Retinal imaging, wide-field; interpretation and report | Provides complementary retinal perfusion and structural information relevant to ocular blood flow assessment |
99214 | Office or other outpatient established patient visit, moderate complexity | Typical E/M visit level during which diagnostic testing is ordered, reviewed, and results discussed; often billed the same day as diagnostic procedures |