Billing code 66184: Shunt revisionMedicare rate & RVUs in Guam
Revision of an existing glaucoma drainage shunt without a graft, reported when the surgeon corrects a shunt problem rather than placing a new device.
CMS doesn’t publish an office rate for 66184 in Guam.
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 66184 covers
An ophthalmic surgeon, often a glaucoma specialist, revises an existing aqueous shunt used to control intraocular pressure. The work may address a tube or reservoir problem, such as obstruction or malposition, to restore drainage or improve shunt function. This code distinguishes revision without a graft from revision that includes graft material, which is reported with 66185.
Select the code from the operative report’s description of the revision and whether graft material was used; do not use it for initial shunt placement. Documentation should identify the existing device, the problem addressed, the revision performed, and graft use or nonuse. Medicare 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 others at 50%. Bilateral reporting with modifier 50 is paid at 150%. An assistant at surgery may be paid; co-surgeons and team surgery are 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.
66184 in Hawaii, Guam
| Payment locality | Office | Facility |
|---|---|---|
| Hawaii, Guam | Unavailable | $724.09 |
How the 66184 rate is calculated
Each of 66184’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 · 66184
RVUs × geographic indexes × conversion factor
Work9.34
9.34 RVUs× 1.000 GPCI
Practice expense10.47
10.47 RVUs× 1.000 GPCI
Malpractice0.75
0.75 RVUs× 1.000 GPCI
Adjusted RVUs
20.5600
Conversion factor
$33.4009
Medicare rate
$686.72
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 66184
66184 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 66184
Shunt revision
| 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) | 0 | Not permitted. |
| 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 · 66184
Shunt revision
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
66184 without 50 · national facility
$686.72
Shunt revision
66184-50 · Bilateral: 150%
$1,030.08
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).
66184 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 66185Shunt revision
- Use 66185 when graft material is part of the aqueous shunt revision; 66184 is the revision without a graft.
- 66179Glaucoma shunt
- 66179 represents initial aqueous shunt placement without a graft. Use 66184 when the surgeon revises an existing shunt without a graft.
- 66180Glaucoma shunt
- 66180 represents initial aqueous shunt placement with a graft; it is not the code for revising an existing shunt.
66184 billing questions
How is 66184 distinguished from 66185?
66184 is for aqueous shunt revision without a graft. Report 66185 when the revision includes a graft.
Can 66184 be reported for initial shunt placement?
No. It describes revision of an existing shunt; initial placement is represented by an insertion code such as 66179, 66180, or 66183, depending on the procedure.
What should the operative report document?
The report should identify the existing shunt, the problem being corrected, the revision performed, and whether graft material was used.
How is bilateral 66184 reported?
For bilateral surgery, report modifier 50. CMS pays the bilateral procedure at 150%.
What postoperative care is included?
The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care.
Can an assistant surgeon be reported?
Assistant-at-surgery payment may be made. CMS does not permit co-surgeons or team surgery for this code.
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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