Billing code 66174: CanaloplastyMedicare rate & RVUs in Illinois
Reports internal dilation of the eye’s aqueous drainage canal for glaucoma when the surgeon leaves no stent or other device in place.
CMS doesn’t publish an office rate for 66174 in Illinois.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 66174 covers
An ophthalmologist reaches the drainage angle from inside the eye and enlarges Schlemm canal to improve aqueous outflow, leaving no implant or stent behind. The procedure is used to lower intraocular pressure in glaucoma and is typically performed in an operating room with gonioscopic visualization by an ophthalmologist, often one with glaucoma surgical expertise.
Report 66174 when the canal is dilated without a retained device; use 66175 when a device or stent remains. The operative report should identify the treated eye, the canal-dilation work, and whether an implant was left in place. CMS assigns a 90-day global period, including the day-before preoperative visit and 90 days of related postoperative care. In a same-session multiple-procedure claim, the highest-valued procedure is paid in full and other procedures at 50%. Modifier 50 bilateral payment is 150%. An assistant at surgery may be paid; co-surgeons require supporting documentation, and team surgery is not permitted.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 66174 pays more and less in Illinois
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
| Payment locality | Office | Facility |
|---|---|---|
| Chicago | Unavailable | $568.62 |
| East St. Louis | Unavailable | $538.24 |
| Rest Of Illinois | Unavailable | $527.59 |
| Suburban Chicago | Unavailable | $564.49 |
How the 66174 rate is calculated
Each of 66174’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 66174
RVUs × geographic indexes × conversion factor
Work7.43
7.43 RVUs× 1.000 GPCI
Practice expense8.17
8.17 RVUs× 1.000 GPCI
Malpractice0.58
0.58 RVUs× 1.000 GPCI
Adjusted RVUs
16.1800
Conversion factor
$33.4009
Medicare rate
$540.43
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 66174
66174 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 66174
Canaloplasty
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 090 | Major surgery: the day before, the day of, and 90 days after are included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| Bilateral (modifier 50) | 1 | Bilateral with modifier 50 pays 150% of the fee schedule amount. |
| Assistant at surgery (80/81/82/AS) | 2 | Paid. |
| Co-surgeons (62) | 1 | Permitted with supporting documentation. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
| Split (54/55/56) | 0.10/0.70/0.20 | Share of the payment for pre-op, the procedure itself, and post-op care. |
Global surgery period · 66174
Canaloplasty
90-day global period ends
Dec 30, 2026
Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).
Visit on Oct 31, 2026
Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.
Pre-op dayGlobal period
What modifiers do to the payment
Modifier 50 · payment effect
With and without the modifier
66174 without 50 · national facility
$540.43
Canaloplasty
66174-50 · Bilateral: 150%
$810.64
Both sides on one line with modifier 50 are paid at 150% of the fee schedule amount (subject to multiple-procedure rules with other procedures).
66174 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 66175Canal dilation
- Both describe internal canal-based glaucoma surgery. Choose 66174 when no device or stent is retained and 66175 when one remains.
- 66179Glaucoma shunt
- 66179 describes aqueous shunt surgery without a graft; 66174 dilates the eye’s drainage canal without leaving a device or stent.
- 66183Drainage device
- 66183 is for insertion of an anterior-segment drainage device. 66174 is canal dilation without a retained device or stent.
- 66170Trabeculectomy
- 66170 represents filtering surgery, while 66174 uses an internal canal-based approach to improve aqueous outflow.
66174 billing questions
How does 66174 differ from 66175?
Use 66174 when the canal is dilated and no device or stent is left in the eye. Use 66175 when a device or stent remains.
Can 66174 be reported with cataract surgery?
It may be performed in the same session as cataract extraction when both services are carried out and documented. CMS applies its same-session multiple-procedure payment reduction.
What documentation supports 66174?
The operative report should describe the internal approach, the canal-dilation work, the eye treated, and whether any device or stent was retained.
How is bilateral 66174 reported?
CMS lists this as a bilateral procedure paid at 150% with modifier 50. The documentation should support treatment of both eyes.
What postoperative care is included?
The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care.
May an assistant or co-surgeon be paid?
An assistant at surgery may be paid. Co-surgeons are paid only with supporting documentation; team surgery is not permitted.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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