Billing code 66185: Shunt revisionMedicare rate & RVUs in Guam
Revision of an existing glaucoma aqueous shunt that includes graft placement, such as patching exposed tubing to protect the implant.
CMS doesn’t publish an office rate for 66185 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 66185 covers
An ophthalmic surgeon revises an existing aqueous shunt used to manage glaucoma and places a graft as part of the repair. A common clinical situation is coverage of exposed shunt tubing with a patch graft. The service is generally performed in an operating room when an implanted drainage device needs surgical correction and graft material is used.
Report this code when the operative documentation supports revision of an existing shunt and use of a graft; revision without a graft is reported with 66184. Document the affected eye, the reason for revision, the work performed on the shunt, and graft placement. 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 is paid at 150% for bilateral surgery. Assistant-at-surgery payment may be made; 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.
66185 in Hawaii, Guam
| Payment locality | Office | Facility |
|---|---|---|
| Hawaii, Guam | Unavailable | $771.28 |
How the 66185 rate is calculated
Each of 66185’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 · 66185
RVUs × geographic indexes × conversion factor
Swap in your local Medicare rate.
Work 10.32Practice expense 10.81Malpractice 0.83
All indexes start at 1.000 (the national rate). Enter a ZIP or drag a slider.
Payment rules and modifiers for 66185
66185 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 66185
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 · 66185
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
66185 without 50 · national facility
$733.48
Shunt revision
66185-50 · Bilateral: 150%
$1,100.22
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).
66185 compared with similar codes
Compare codes
66185 vs 66184 vs 66180 vs 66179 vs 66183: national Medicare rates
Swap in your local Medicare rate.
How to choose
- 66184Shunt revision
- Both describe revision of an aqueous shunt to an extraocular reservoir. Choose 66185 when a graft is used and 66184 when the revision is without a graft.
- 66180Glaucoma shunt
- 66180 describes initial placement of an aqueous shunt with graft. Use 66185 when revising an existing shunt and placing a graft.
- 66179Glaucoma shunt
- 66179 describes initial aqueous shunt placement without graft; 66185 is for graft-involving revision of an existing shunt.
- 66183Drainage device
- 66183 is insertion of an anterior-segment drainage device without an extraocular reservoir. It is not revision of an existing reservoir shunt.
66185 billing questions
How is 66185 different from 66184?
66185 is for aqueous shunt revision with graft placement. Use 66184 when the revision is performed without a graft.
Does this code describe initial shunt placement?
No. It describes revision of an existing aqueous shunt with a graft. Initial placement is a different service, such as the procedures represented by 66179 or 66180.
What documentation supports reporting 66185?
Document the existing shunt, the reason for revision, the work performed, and that graft material was placed. Include the eye treated.
How is bilateral revision reported under the CMS facts?
For bilateral surgery, modifier 50 is paid at 150% under the CMS rule for this code.
What is included in the global period?
The 90-day global includes the day-before preoperative visit and 90 days of related postoperative care.
Can an assistant or co-surgeon be reported?
Assistant-at-surgery payment may be made. Co-surgeons and team surgery are not permitted 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
Fee sheets
Put 66185 and the rest of your codes on one sheet
Build a fee sheet from your own code list at your locality, put your payer contracts beside Medicare, and see what changed each quarter.
Build my fee sheetOr price your code list free →