Summary & Overview
CPT 66174: Expansion of Aqueous Outflow Canal Without Stent
CPT code 66174 captures a glaucoma-related surgical procedure that expands the eye's aqueous outflow (drainage) canal without placing a device or stent. Nationally relevant for ophthalmology practices and surgical centers, the code distinguishes non-implant canaloplasty or trabecular expansion techniques from device-based interventions and affects coding, billing, and clinical documentation for glaucoma pressure-management procedures. Key payers in typical analyses include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
This publication explains the clinical intent of CPT code 66174, clarifies common service settings and procedural scope, and summarizes what readers can expect about coverage and billing practice differences across major payers. Topics covered include procedural definition and clinical context, common billing considerations, typical sites of service, and where to look for payer-specific coverage guidance. The content highlights how the code is used in surgical workflows and documentation, and identifies areas where payers commonly request additional supporting information. Data not available in the input is noted where payer-specific policies, reimbursement rates, or associated ICD-10 mappings would normally be detailed.
Billing Code Overview
CPT code 66174 describes a surgical procedure in which the provider expands the eye's aqueous outflow (drainage) canal to relieve intraocular pressure. The description specifies that the procedure does not include leaving a device or stent in place, distinguishing it from canal-based procedures that implant permanent or temporary devices.
Service Type: Ophthalmic surgical procedure — anterior segment, glaucoma drainage augmentation (non-implant)
Typical Site of Service: Hospital outpatient department or ambulatory surgical center (eye surgery specialty settings are typical)
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient with primary open-angle glaucoma presents with progressive intraocular pressure (IOP) elevation despite maximally tolerated topical therapy and prior selective laser trabeculoplasty. The ophthalmologist schedules a minimally invasive surgical procedure to expand the aqueous outflow canal without leaving a permanent stent in place to reduce IOP. Typical workflow: preoperative evaluation with visual acuity, IOP measurement, gonioscopy, and ocular surface assessment; informed consent documenting risks/benefits; intraoperative use of operating microscope and microcatheter or viscodilation technique to dilate Schlemm canal via a small corneal incision; intraoperative confirmation of improved outflow; postoperative topical antibiotics and anti-inflammatory drops with IOP checks at day 1, week 1, and month 1. Typical site of service is an ambulatory surgery center or hospital outpatient department. Service type: ophthalmic microinvasive glaucoma surgery (canaloplasty/viscodilation without stent) to expand the aqueous drainage canal and relieve intraocular pressure.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the physician's professional portion and technical component billed separately. |
50 |