CPT code 66170: Trabeculectomy, without prior scarring2026 Medicare rate & RVUs in Missouri
Reports an ab externo trabeculectomy to lower intraocular pressure by creating a guarded drainage pathway, without scarring from prior ocular surgery or trauma.
CMS doesn’t publish an office rate for 66170 in Missouri.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
Your location
On this page 9 sections
What 66170 covers
An ophthalmic surgeon performs this filtering operation to lower intraocular pressure, commonly for glaucoma that remains inadequately controlled with medication or laser treatment. The surgeon creates a guarded opening through the sclera so aqueous fluid can drain beneath the conjunctiva and form a filtering bleb. This code describes the procedure without scarring from previous ocular surgery or trauma; the presence of such scarring distinguishes the related 66172 service. The procedure is typically performed in an operating room, and the operative report should identify the eye, surgical approach, and relevant prior ocular history.
Report the service for the eye treated. 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 the same session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% multiple-procedure reduction. For bilateral surgery, modifier 50 is paid at 150%. Assistant-at-surgery payment may be made; co-surgeon payment requires 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 66170 pays more and less in Missouri
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | Unavailable | $910.07 |
| Metropolitan St. Louis, MO | Unavailable | $916.80 |
| Rest of Missouri | Unavailable | $875.47 |
How the 66170 rate is calculated
Each of 66170’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 · 66170
RVUs × geographic indexes × conversion factor
Work13.59
13.59 RVUs× 1.000 GPCI
Practice expense13.41
13.41 RVUs× 1.000 GPCI
Malpractice1.09
1.09 RVUs× 1.000 GPCI
Adjusted RVUs
28.0900
Conversion factor
$33.4009
Medicare rate
$938.23
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 66170
66170 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 66170
Trabeculectomy, without prior scarring
| 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 · 66170
Trabeculectomy, without prior scarring
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
66170 without 50 · national facility
$938.23
Trabeculectomy, without prior scarring
66170-50 · Bilateral: 150%
$1,407.35
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).
66170 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 66172Glaucoma surgeryPrior surgery or trauma scarring
- Choose 66170 for trabeculectomy without the specified prior-surgery or trauma scarring; 66172 is the corresponding service when that scarring is present.
- 66174CanaloplastyWithout retained stent
- 66174 describes transluminal dilation of the aqueous outflow canal without a retention device. It is a different approach from creating a trabeculectomy filtration pathway.
- 66180Glaucoma shuntWith graft
- 66180 involves aqueous shunt surgery with a graft. 66170 is a trabeculectomy rather than implantation of that shunt.
66170 billing questions
When should 66172 be considered instead?
Use 66172 when scarring from previous ocular surgery or trauma is present. The operative documentation should support which condition applies.
How is bilateral trabeculectomy reported?
For bilateral surgery, report modifier 50; CMS pays this code at 150%.
Does the global period include postoperative visits?
Yes. The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care.
How does the multiple-procedure reduction work?
When other procedures are performed in the same session, the highest-valued procedure is paid in full and the others are paid at 50%.
Can an assistant or co-surgeon be reported?
Assistant-at-surgery payment may be made. Co-surgeon payment requires supporting documentation; team surgery is not permitted.
What should the operative note establish?
Document the eye treated, the ab externo filtering procedure performed, and whether scarring from prior ocular surgery or trauma is present.
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
Fee sheets
Put 66170 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Build my fee sheet