Eye Care Coding Reference
CPT 66821 YAG laser capsulotomy.
What the code covers, its 90-day global period, billing a YAG inside the cataract global, the documentation Medicare contractors look for, repeat treatment limits and related codes. Last reviewed October 2026.
In one paragraph
The code for clearing a cloudy capsule.
CPT 66821 covers opening a clouded posterior lens capsule with a laser, most often an Nd:YAG laser, after cataract surgery. Medicare lists it with a 90-day global period, and the code covers the whole capsulotomy for that eye even when the laser work takes more than one session. When the YAG falls inside the cataract surgery global period for the same eye, AAO guidance uses modifier 78, though payer rules differ. Medicare contractors expect the record to show posterior capsule opacification that limits the patient's daily activities. Descriptions on this page are Vision Rescue summaries, not the official CPT descriptor.
66821 at a glance
- Global period: 90 days
- Eye modifiers: RT or LT on every claim
- Same eye inside the cataract global: AAO guidance uses modifier 78
- Other eye inside the cataract global: modifier 79
- Common diagnoses: ICD-10-CM H26.4 family
- Usually covered once per eye
The 90-day global period.
Medicare's fee schedule assigns 66821 a 90-day global period, the same length as cataract surgery. The package runs from the day before the laser through 90 days after.
Included in the package
- Pre-procedure visits from the day before the laser
- The laser treatment itself, including any additional sessions for the same eye
- Routine follow-up visits during the 90 days
- Treating complications that do not need a return to the procedure room
Billed separately, with a modifier
| Modifier | When it applies |
|---|---|
| 57 | Exam where the decision to do the YAG was made, the day before or day of the laser |
| 24 | Unrelated exam or visit during the 66821 global period |
| RT or LT | On every 66821 claim line to show the eye treated |
CGS billing article A56493 allows payment once per eye, per patient, per 90-day global period, regardless of how many YAG sessions were needed.
YAG inside the cataract global period.
A YAG done within 90 days of cataract surgery falls inside the cataract global. How it is reported depends on which eye is treated and on the payer.
| Situation | Modifier commonly cited | What it means for payment |
|---|---|---|
| YAG on the same eye as the recent cataract surgery | 78 with RT or LT (AAO guidance) | No new global period starts; only the procedure portion is paid and the cataract global continues |
| YAG on the other eye | 79 with RT or LT | Treated as unrelated; a new 90-day global starts for 66821 |
| YAG after the cataract global has ended | RT or LT only | Billed as a standalone procedure with its own 90-day global |
Guidance differs. AAO advises modifier 78 for the same eye because the capsule opacity is related to the cataract surgery, while some payers and coders expect modifier 79. Some payers, including some Medicare contractors, limit or deny coverage of 66821 during the cataract global. Check your contractor's policy before the claim goes out.
Medicare contractor policy notes that significant capsule opacification is uncommon within three months of cataract surgery. CGS asks for documentation that justifies a capsulotomy done in that window, and Medicare does not cover a capsulotomy done or scheduled at the same session as the cataract removal.
Medical necessity and documentation.
CGS LCD L33946 describes YAG capsulotomy as reasonable only to treat a functional problem caused by capsule opacification. Policies vary by contractor, but these elements appear often.
What the record should show
- A patient complaint that the vision limits daily activities, such as reading or driving
- Best-corrected acuity of 20/50 or worse at distance or near, or a two-line drop with glare or consensual light testing
- Exam findings describing the capsule opacity in the treated eye
- Other eye disease ruled out as the main cause of the vision loss
- Risks, benefits and alternatives discussed, with consent
- A signed procedure note that names the eye
ICD-10-CM codes listed by CGS
| ICD-10-CM | Covers |
|---|---|
| H26.40 | Unspecified secondary cataract |
| H26.411 to H26.413 | Soemmering's ring, right, left or both eyes |
| H26.491 to H26.493 | Other secondary cataract, right, left or both eyes |
| T85.21XA, T85.22XA, T85.29XA | Mechanical complications of an intraocular lens, initial encounter |
Under the CGS policy, acuity of 20/40 or better may still qualify if all other criteria are met and documented. Medicare Advantage, Medicaid and commercial plans may add prior authorization or their own acuity thresholds.
Repeat capsulotomy limits.
- Medicare contractor policy expects a capsulotomy to be needed no more than once per eye
- Extra laser sessions to finish the same opening are part of the original 66821
- A second capsulotomy on the same eye needs a documented reason, such as a condition unrelated to the cataract surgery that raises the risk of re-opacification
- Some contractors may review a repeat claim before paying it
The code itself did not change. Medicare's 2026 fee schedule applied an efficiency adjustment to most procedure codes and shifted indirect practice expense away from facility settings, which widened the gap between office and ASC payment for YAG capsulotomy.
From Vision Rescue Pro
Supplies for cataract and comprehensive practices.
Separate from the coding information above. Vision Rescue Pro is a licensed distributor serving practices that perform YAG capsulotomy and co-manage cataract care.
- In-office Rx at wholesale, including dilation drops and anesthetics
- Price Match Guarantee
- Post-procedure care plans by text with RescueLink
- Ships to your office
Questions about CPT 66821
What is CPT code 66821?
It is the code for opening a clouded posterior lens capsule with a laser, usually an Nd:YAG laser, after cataract surgery. It is often called a YAG capsulotomy.
What is the global period for 66821?
Medicare lists 66821 with a 90-day global period. The package covers the day before, the day of the laser and 90 days after.
What modifier is used for 66821 during the cataract global period?
For the same eye, AAO guidance uses modifier 78 with RT or LT, and no new global period starts. For the other eye, modifier 79 applies. Some payers expect 79 for the same eye too, and some limit coverage in the global, so check your contractor.
How often can 66821 be billed?
Medicare contractor policy expects it once per eye. More sessions to complete the same opening are included, and a true repeat needs documented medical reasons.
What diagnosis supports 66821?
Contractor policies list secondary cataract codes such as H26.40, H26.41- and H26.49-, plus certain intraocular lens complication codes. A listed code alone does not assure coverage.
Sources
CMS Medicare Physician Fee Schedule indicators for 66821; CMS MLN Global Surgery Booklet (MLN907166); Medicare NCCI Policy Manual, Chapter 8, 2026; CGS LCD L33946 and billing article A56493, Capsule Opacification Following Cataract Surgery; AAO practice management guidance on YAG in the global period; AAO EyeNet coding articles on Nd:YAG capsulotomy and modifiers; AAPC coding newsletter on YAG and cataract globals; Review of Ophthalmology, Coding and Reimbursement 2026 Update; CMS ICD-10-CM FY2026 code set.
Notes and disclosures
CPT is a registered trademark of the American Medical Association. Descriptions here are Vision Rescue summaries, not official CPT descriptors. This page is general information for eye care professionals and billing staff, not legal, billing or coding advice. Payer rules vary; verify codes, modifiers and coverage with the current official code sets, your Medicare contractor and the patient's plan. Questions: providers@visionrescue.com or 1-855-692-8024.
Code the YAG right, then stock the room.
Dilation drops, anesthetics and post-procedure follow-through for cataract and comprehensive practices.