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Billing code 66175: Canal dilationMedicare rate & RVUs

Reports glaucoma surgery that dilates the aqueous outflow canal and leaves a stent or other device in place to support drainage.

CMS RVU26DEffective Oct 1, 2026109 payment localities470 Medicare services in 2024

Medicare pays $620.25 for 66175 nationally in a facility.

Medicare rate · 66175

Canal dilation

Swap in your local Medicare rate.

Work RVUs
9.11
Total RVUs
18.57
Global days
090

National rate · 2026

$620.25

Facility setting, before claim adjustments.

See every locality for 66175 → · Billed by an NP, PA or therapist? →

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 10 sections
  1. Medicare rate
  2. What 66175 covers
  3. By payment locality
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Similar codes
  8. Related codes
  9. Billing questions
  10. Sources

What 66175 covers

An ophthalmic surgeon treats impaired aqueous drainage by passing an instrument through the outflow canal, dilating it, and leaving a stent or other device in place. The procedure is used for glaucoma when improving flow through the eye’s natural drainage pathway is the surgical goal. It is generally performed in an operating room, often with gonioscopic visualization, and may be done during the same session as cataract surgery.

Report 66175 when canal dilation includes retention of a device or stent; documentation should identify the treated eye, the dilation procedure, and the retained device. Dilation without a retained device is reported with 66174. CMS assigns a 90-day global period, including the day-before preoperative visit and 90 days of related postoperative care. When multiple procedures are performed in one session, the highest-valued is paid in full and others at 50%. Bilateral reporting with modifier 50 is paid at 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 66175 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

66175 office and facility rates by payment locality
Payment localityOfficeFacility
AlabamaUnavailable$573.33
Alaska*Unavailable$780.57
ArizonaUnavailable$607.74
ArkansasUnavailable$567.43
AtlantaUnavailable$630.67
AustinUnavailable$635.05
BakersfieldUnavailable$644.66
Baltimore/Surr. CntysUnavailable$652.13
BeaumontUnavailable$592.27
BrazoriaUnavailable$614.77

66175 rates by state

Office rate range in each state. Select a state to see its payment localities.

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Local rates. Clear comparisons.

Hover or focus a tile to see its rate range. Select it to open the state’s fee schedule.

View every state and territory as a table
66175 office rate range by state
State / territoryOffice rate rangeLocalities
AKNo published base rate1
ALNo published base rate1
ARNo published base rate1
AZNo published base rate1
CANo published base rate29
CONo published base rate1
CTNo published base rate1
DCNo published base rate1
DENo published base rate1
FLNo published base rate3
GANo published base rate2
GUNo published base rate1
HINo published base rate1
IANo published base rate1
IDNo published base rate1
ILNo published base rate4
INNo published base rate1
KSNo published base rate1
KYNo published base rate1
LANo published base rate2
MANo published base rate2
MDNo published base rate3
MENo published base rate2
MINo published base rate2
MNNo published base rate1
MONo published base rate3
MSNo published base rate1
MTNo published base rate1
NCNo published base rate1
NDNo published base rate1
NENo published base rate1
NHNo published base rate1
NJNo published base rate2
NMNo published base rate1
NVNo published base rate1
NYNo published base rate5
OHNo published base rate1
OKNo published base rate1
ORNo published base rate2
PANo published base rate2
PRNo published base rate1
RINo published base rate1
SCNo published base rate1
SDNo published base rate1
TNNo published base rate1
TXNo published base rate8
UTNo published base rate1
VANo published base rate2
VINo published base rate1
VTNo published base rate1
WANo published base rate2
WINo published base rate1
WVNo published base rate1
WYNo published base rate1

How the 66175 rate is calculated

Each of 66175’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 · 66175

RVUs × geographic indexes × conversion factor

Swap in your local Medicare rate.

Work 9.11Practice expense 8.74Malpractice 0.72

18.5700 adjusted RVUs×$33.4009 conversion factor=$620.25

All indexes start at 1.000 (the national rate). Enter a ZIP or drag a slider.

Payment rules and modifiers for 66175

66175 has a 90-day global period: related visits in that window are included in the surgery payment.

CMS payment indicators · 66175

Canal dilation

RuleCMS valueWhat it means
Global period090Major surgery: the day before, the day of, and 90 days after are included.
Multiple procedures2Standard reduction: highest-valued procedure at 100%, others at 50%.
Bilateral (modifier 50)1Bilateral with modifier 50 pays 150% of the fee schedule amount.
Assistant at surgery (80/81/82/AS)2Paid.
Co-surgeons (62)1Permitted with supporting documentation.
Team surgery (66)0Not permitted.
Professional/technical0Physician service: no professional/technical split.
Split (54/55/56)0.10/0.70/0.20Share of the payment for pre-op, the procedure itself, and post-op care.

Global surgery period · 66175

Canal dilation

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.

  • 24 Unrelated E/M visit by the same physician
  • 79 Unrelated procedure (starts its own global period)
  • 58 Staged, more extensive, or therapy procedure that was planned
  • 78 Unplanned return to the operating room for a related complication
SurgeryVisit
Sep 23, 2026Jan 10, 2027

Pre-op dayGlobal period

What modifiers do to the payment

Modifier 50 · payment effect

With and without the modifier

66175 without 50 · national facility

$620.25

Canal dilation

66175-50 · Bilateral: 150%

$930.38

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).

When to use modifier 50

66175 compared with similar codes

Compare codes

66175 vs 66174 vs 66183 vs 66179 vs 66180: national Medicare rates

Swap in your local Medicare rate.

  • 66175
    Canal dilation · 9.11 wRVU
    —
  • 66174
    Canaloplasty · 7.43 wRVU
    —
  • 66183
    Drainage device · 12.87 wRVU
    —
  • 66179
    Glaucoma shunt · 13.65 wRVU
    —
  • 66180
    Glaucoma shunt · 14.63 wRVU
    —

How to choose

66174Canaloplasty
Both codes describe transluminal dilation of the aqueous outflow canal. Choose 66175 when a device or stent remains in place; choose 66174 when none is retained.
66183Drainage device
66183 describes insertion of an anterior drainage device. 66175 is for dilation of the aqueous outflow canal with a device or stent retained there.
66179Glaucoma shunt
66179 describes aqueous shunt surgery without a graft. Choose it for shunt placement rather than canal dilation with a retained stent.
66180Glaucoma shunt
66180 describes aqueous shunt surgery with a graft. It is a different drainage procedure from dilation of the outflow canal under 66175.

Codes related to 66175

Related codes aren’t interchangeable: bill the code that matches the service performed.

Codes related to 66175
CodeHow it relatesNational office range
Same family
66174CanaloplastyCanal dilation without retention of a device or stent.No office rate
Used instead
66179Glaucoma shuntAqueous shunt surgery without graft, rather than dilation with a retained canal device.No office rate
66180Glaucoma shuntAqueous shunt surgery with graft; a different drainage operation.No office rate
66183Drainage deviceInsertion of an anterior drainage device, rather than dilation of the outflow canal.No office rate
Often billed with
66984Cataract surgeryCataract extraction may be performed during the same session as canal dilation.No office rate

66175 billing questions

How do I choose between 66175 and 66174?

Use 66175 when a stent or other device is left in place after canal dilation. Use 66174 for canal dilation without a retained device.

Is the retained stent separately reported?

The retained device is part of the service represented by 66175. Do not report a separate code just for leaving that device in place.

Can 66175 be reported with cataract surgery?

It may be performed during the same session as cataract extraction. Document each procedure performed and apply the applicable same-session coding rules.

What supports reporting 66175?

The operative report should identify the treated eye, canal dilation, and the device or stent left in place. Those details distinguish this service from dilation without retained hardware.

How is bilateral 66175 reported under the CMS facts?

Use modifier 50 for a bilateral procedure; CMS pays it at 150%.

Does the 90-day global include related follow-up?

Yes. The global period includes the day-before preoperative visit and 90 days of related postoperative care.

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
RVUs for 66175PPRRVU2026_Oct_nonQPP.csv, line 7,369 (RVU26D)

Open CMS sourceHow we calculate rates

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