On this page
- What Is Modifier 79?
- How Is Second-Eye Cataract Surgery Billed?
- Which Eye Care Procedures Use Modifier 79?
- How Is Modifier 79 Different From 78 and 58?
- Is Second-Eye Cataract Surgery Paid in Full?
- How Do the Two Global Periods Overlap?
- How Does Modifier 79 Change the Global Period?
- Why Do Modifier 79 Claims Deny?
Key takeaways
- Modifier 79 is used on a procedure, not a visit, during another procedure's global period.
- Second-eye cataract surgery is billed with modifier 79 and the eye modifier, for example 66984-79-LT.
- A procedure billed with modifier 79 starts its own new global period.
- A related return to the operating room uses modifier 78, and a planned staged procedure uses 58.
What Is Modifier 79?
Modifier 79 is a CPT modifier for a procedure or service performed by the same physician or group during the postoperative period of an earlier procedure, when the new procedure is unrelated to the first. Without it, the payer assumes the second procedure is part of the first one's global package.
Modifier 79 is for procedures. An unrelated office visit during a global period uses modifier 24 instead.
How Is Second-Eye Cataract Surgery Billed?
Second-eye cataract surgery during the first eye's global period is billed with the cataract code, modifier 79 and the eye modifier. A typical claim reads 66984-79-LT when the right eye was done first.
Medicare contractors such as Palmetto GBA use this exact example, because the second surgery treats a different eye. The record must still show that each eye had its own indication for surgery. Our cataract surgery billing page covers bilateral timing and premium lens charges.
Which Eye Care Procedures Use Modifier 79?
Modifier 79 is used for any unrelated procedure during a global period, and eye care has a few that come up every week. The table lists the most common ones.
| Procedure during a global period | Usual modifier |
|---|---|
| Cataract surgery on the second eye | 79 with RT or LT |
| YAG capsulotomy after cataract surgery in the same eye | Commonly 79, check the payer |
| Laser for a new retinal tear after cataract surgery | 79 |
| Unplanned return to surgery for a related complication | 78 |
| Planned second stage of the same treatment | 58 |
The question that decides the modifier is whether the new procedure treats the same problem as the first one. If it treats a different problem or a different eye, modifier 79 usually applies.
How Is Modifier 79 Different From 78 and 58?
Modifier 79 is for an unrelated procedure, modifier 78 is for an unplanned return to the operating room for a related problem and modifier 58 is for a planned or staged procedure. All three apply during a global period, so the relationship to the first surgery decides which one fits.
| Modifier | Relationship to the first surgery | New global period? | Eye care example |
|---|---|---|---|
| 79 | Unrelated | Yes | Cataract surgery on the second eye |
| 78 | Related, unplanned, back to the operating room | No | Surgery for a complication of the first operation |
| 58 | Related, planned or staged | Yes | A planned second laser session |
Choosing 78 instead of 79 for a second-eye surgery is a common error that lowers payment.
Is Second-Eye Cataract Surgery Paid in Full?
Second-eye cataract surgery on a different day, billed with modifier 79, is paid as its own procedure under the payer's normal rules. Same-day surgery on both eyes is billed differently, with modifier 50 or RT and LT lines, and bilateral payment rules apply.
Payer rules differ, and some plans review 79 claims before paying. Check each payer's policy and keep the indication for each eye in the record. Our cataract surgery billing page covers bilateral timing in more detail.
Does modifier 79 need RT or LT?
Yes, on every eye procedure. The eye modifier shows the payer that the second surgery treated a different eye, which is the reason modifier 79 applies.
How Do the Two Global Periods Overlap?
After second-eye surgery, two global periods run at the same time, one for each eye, and every visit is checked against both. The example shows right eye surgery on March 1 and left eye surgery on March 15.
| Visit | Global period it falls in | How it is billed |
|---|---|---|
| March 16, left eye post-op check | Left eye global | Included, no charge |
| April 10, right eye post-op check | Right eye global | Included, no charge |
| April 20, new unrelated problem | Both globals | Exam with modifier 24 |
| June 20, routine follow-up | Both globals ended | Normal visit, no modifier |
Tracking both end dates in the billing system prevents billing visits that are already paid for in the surgery.
How Does Modifier 79 Change the Global Period?
A procedure billed with modifier 79 starts its own global period, which runs at the same time as whatever remains of the first one. Visits after the second surgery are then checked against both global periods.
A visit for the second eye inside its new global period is part of that surgery. A visit for a new problem in either eye may need modifier 24.
Why Do Modifier 79 Claims Deny?
Modifier 79 claims deny most often because the eye modifier is missing, the record does not show the procedures are unrelated or the payer has its own policy. These steps prevent most of them.
- Add the eye. Bill RT or LT with modifier 79 on every eye procedure.
- Document each indication. Show why the new procedure was needed on its own.
- Check the payer. Some commercial and Medicare Advantage plans review 79 claims more closely.
- Track global dates. Know when each global period starts and ends.
Our ophthalmology medical coding services check every procedure inside a global period before the claim is sent.