CPT code 00147 identifies anesthesia services provided for an iridectomy — the surgical excision of a portion of the iris, typically performed to reduce intraocular pressure in glaucoma patients or to address structural iris abnormalities. This code falls within the anesthesia for procedures on the eye subsection of the AMA CPT code set and carries 4 base units per the CMS nationwide anesthesia base unit schedule. Understanding how to bill, document, and select 00147 correctly is essential for anesthesia billing teams, ophthalmology practices with in-house anesthesia, and revenue cycle professionals managing eye surgery claims.
What Does CPT Code 00147 Mean?
CPT 00147 describes anesthesia administered by a qualified anesthesia provider — an anesthesiologist (MD/DO) or certified registered nurse anesthetist (CRNA) — during an iridectomy procedure. An iridectomy involves removing a small section of the iris to create a new pathway for aqueous humor drainage, most commonly indicated for angle-closure glaucoma or as part of a combined ophthalmic procedure.
Key attributes of CPT 00147:
- Code category: Anesthesia for procedures on the eye (Head subsection, 00100–00222 range)
- Billable provider types: Anesthesiologist (MD/DO), CRNA, anesthesiologist assistant (AA) under supervision
- Applicable surgical setting: Hospital outpatient, ambulatory surgery center (ASC), inpatient
- Base units: 4 (per CMS/ASA anesthesia base unit schedule)
- Billing methodology: Base units + time units × locality-specific anesthesia conversion factor
- Global period: 0 days (anesthesia codes carry no global period)
What Services and Procedures Does CPT 00147 Cover?
CPT 00147 applies specifically to the anesthesia component of iridectomy procedures. It captures the full scope of anesthesia care rendered in the perioperative period — from pre-induction assessment through emergence and immediate post-anesthesia stabilization.
Clinical presentations and procedure types covered under 00147:
- Surgical iridectomy for primary angle-closure glaucoma
- Iridectomy performed as part of glaucoma drainage device implantation (where iridectomy is the primary anesthetic event)
- Laser iridotomy cases requiring IV sedation or monitored anesthesia care (MAC) rather than simple topical anesthetic
- Iridectomy for iris cysts, neoplasms, or traumatic iris root dialysis requiring formal anesthetic management
- Peripheral iridectomy combined with other anterior segment procedures when 00147 represents the highest-valued anesthesia service for the session
What Does CPT 00147 Specifically Exclude?
CPT 00147 does not apply in the following situations:
- Anesthesia for lens surgery (cataract, IOL) — report CPT 00142 instead
- Anesthesia for corneal transplant procedures — report CPT 00144
- Anesthesia for vitreoretinal procedures — report CPT 00145
- Anesthesia for ophthalmoscopy or diagnostic eye exam — report CPT 00148
- Anesthesia for general eye procedures not otherwise specified — report CPT 00140
- The iridectomy surgical procedure itself — the operative CPT code (e.g., 66680 or 66761) is reported by the surgeon separately; 00147 covers anesthesia only
- Local anesthetic infiltration administered by the surgeon — not separately reportable as 00147
When Is CPT 00147 the Right Code to Use?
Correct code selection for anesthesia eye procedures depends on matching the anesthetic event to the primary surgical procedure performed. 00147 is appropriate when the iridectomy is the primary (or sole) surgical procedure during the anesthesia session.
Step-by-step criteria for selecting CPT 00147:
- Confirm the surgical procedure documented in the operative report is an iridectomy (partial or complete iris excision or laser peripheral iridotomy requiring formal anesthesia).
- Confirm the service was performed by a qualified anesthesia provider — not local anesthetic only administered by the surgeon.
- Verify no higher-valued anesthesia code applies to a concurrent or primary procedure (e.g., if vitreoretinal surgery was also performed, 00145 at 6 base units would supersede 00147 at 4 base units — report only the single code with the highest base unit value).
- Confirm anesthesia start and stop times are documented in the anesthesia record.
- Verify the physical status modifier (P1–P6) is documented and supported by the preanesthesia assessment.
How Does CPT 00147 Differ From Other Eye Anesthesia Codes?
When a patient undergoes a combined procedure, coders must select the single anesthesia code with the highest base unit value. The table below clarifies the distinctions.
| CPT Code | Procedure | Base Units | Key Differentiator |
|---|---|---|---|
| 00140 | Eye procedures, NOS | 5 | Use when no specific eye sub-code applies |
| 00142 | Lens surgery (cataract, IOL) | 4 | Anterior segment, lens-specific |
| 00144 | Corneal transplant | 6 | Full-thickness or lamellar keratoplasty |
| 00147 | Iridectomy | 4 | Iris excision or surgical iridotomy |
| 00145 | Vitreoretinal surgery | 6 | Posterior segment procedures |
| 00148 | Ophthalmoscopy / eye exam | 4 | Diagnostic, non-surgical |
In practice, coders sometimes see iridectomy performed as part of a combined procedure with a corneal transplant. In that scenario, 00144 (6 base units) is the correct single code to report — not 00147 (4 base units) — because payer policy and ASA coding guidelines require reporting only the code with the highest base unit value for concurrent procedures under a single anesthetic.
What Documentation Is Required to Support CPT 00147?
Anesthesia claims are frequently scrutinized during audits and payer reviews. Documentation must substantiate both the anesthesia service itself and the clinical circumstances that guided code and modifier selection.
What Must the Provider Document in the Anesthesia Record?
The following elements are required in the anesthesia record to support a 00147 claim:
- Pre-anesthesia evaluation — documented history, physical status classification (ASA PS I–VI), and planned anesthetic technique
- Anesthesia start time — the moment the anesthesia provider begins preparing the patient for anesthesia (per CMS Medicare Claims Processing Manual, Chapter 12, Section 50)
- Anesthesia stop time — when the anesthesia provider’s personal attendance is no longer required (varies by payer; some require end of procedure, others end of recovery room care)
- Intraoperative monitoring documentation — continuous monitoring of oxygenation, ventilation, circulation, and temperature as applicable
- Anesthetic agents and dosages administered
- Physical status modifier — supported by documented comorbidities (e.g., P2 for a patient with controlled hypertension)
- Qualifying circumstance codes if applicable (e.g., 99100 for patients under age 1 or over age 70)
- Attestation or co-signature when a CRNA performed the service under medical direction
How Do CMS Anesthesia Payment Rules Apply to This Code?
Anesthesia codes including 00147 are not paid under the standard RVU-based Medicare Physician Fee Schedule formula. Instead, reimbursement is calculated as:
(Base Units + Time Units) × Anesthesia Conversion Factor
- Base units for 00147 = 4 (fixed, per CPT/CMS assignment)
- Time units = total anesthesia minutes ÷ 15 (each 15-minute increment = 1 time unit)
- Conversion factor is locality-specific; national Medicare rates vary by MAC jurisdiction
Always verify the current anesthesia conversion factor for your MAC region via the CMS Physician Fee Schedule (PFS) lookup tool.
What Are the Documentation Standards for Facility vs. Non-Facility Settings?
| Requirement | Facility (Hospital/ASC) | Non-Facility |
|---|---|---|
| Anesthesia record | Required — integrated in facility chart | Required — provider-maintained |
| Start/stop time | Required per CMS guidelines | Required |
| Physical status documentation | Documented in pre-op assessment | Documented in provider notes |
| Concurrent procedure documentation | Required when multiple procedures billed | N/A (rare in non-facility) |
| CRNA supervision attestation | Required when MD directing | Required |
How Does CPT 00147 Affect Medical Billing and Reimbursement?
Unlike E&M or surgical codes, anesthesia reimbursement is time-driven and not directly tied to standard work/practice expense/malpractice RVU components. The table below illustrates the base unit context compared to neighboring eye anesthesia codes.
CPT 00147 Base Unit Context and Estimated Reimbursement Framework
| CPT | Procedure | Base Units | Relative Complexity |
|---|---|---|---|
| 00147 | Iridectomy | 4 | Low-to-moderate |
| 00140 | Eye, NOS | 5 | Moderate |
| 00142 | Lens surgery | 4 | Low-to-moderate |
| 00144 | Corneal transplant | 6 | Moderate-high |
| 00145 | Vitreoretinal surgery | 6 | Moderate-high |
For a typical iridectomy with 30 minutes of anesthesia time (2 time units), the formula yields 6 total units (4 base + 2 time). Multiplied by a representative Medicare anesthesia conversion factor of approximately $22–$25 per unit (varies by locality), this yields an approximate Medicare reimbursement of $132–$150 for the anesthesia service. Actual commercial rates vary significantly and should be verified against current contracts.
Payer-specific considerations:
- Medicare reimburses 00147 subject to the MPFS anesthesia schedule and MAC-specific local coverage policies
- Commercial payers may adopt ASA relative value guide base units or apply their own contracted conversion factors
- Modifier AA, QK, QX, QY, or QZ must be present on the claim — missing supervision modifiers are a leading cause of anesthesia claim denials
- Some MACs require ICD-10 diagnosis codes that establish medical necessity for anesthesia (e.g., H40.20x — unspecified primary angle-closure glaucoma)
What Modifiers Are Commonly Used With CPT 00147?
| Modifier | Description | When to Apply | Billing Impact |
|---|---|---|---|
| AA | Anesthesia services performed personally by anesthesiologist | Anesthesiologist provides service without CRNA | 100% of allowance |
| QK | Medical direction of 2–4 CRNAs by anesthesiologist | MD directing multiple concurrent cases | Typically 50% per CRNA case |
| QX | CRNA with medical direction by anesthesiologist | Append to CRNA’s claim in a medically directed case | Used alongside QK on MD’s claim |
| QZ | CRNA without medical direction | CRNA independently providing service | 100% of CRNA allowance |
| QY | Medical direction of one CRNA | One-to-one MD/CRNA | Per payer policy |
| P1–P6 | Physical status modifiers | Always required — reflects patient health at time of procedure | P3+ may attract additional review |
| 23 | Unusual anesthesia | General anesthesia required for a procedure normally done under local | Must document clinical rationale |
| 47 | Anesthesia by surgeon | Surgeon personally administers regional/general anesthesia | Appended to surgical code; no 00147 then billed by surgeon |
| 22 | Increased procedural services | Substantially greater work than typical | Requires supporting documentation |
| 99100 | Qualifying circumstance — extreme age | Patient under 1 year or over 70 | Add-on; billed in addition to 00147 |
| 99140 | Qualifying circumstance — emergency | Emergency anesthesia | Add-on; increases base units |
Are There Any Prior Authorization, Coverage Restrictions, or LCD Requirements?
- Medicare does not uniformly require prior authorization for 00147; however, the surgical iridectomy procedure (reported by the surgeon) may require pre-authorization under Medicare Advantage plans
- Medicaid policies vary by state — several state Medicaid programs require PA for elective ophthalmic surgery and associated anesthesia
- No national coverage determination (NCD) currently governs 00147 specifically
- LCD guidance may apply at the MAC level — verify with your MAC’s published policies for ophthalmic anesthesia
- Anesthesia records must be retained per CMS documentation retention requirements (minimum 5 years for Medicare)
What CPT or HCPCS Codes Are Commonly Billed Alongside CPT 00147?
In ophthalmology and ASC settings, anesthesia for iridectomy is often paired with specific surgical, qualifying circumstance, or supply codes on the same claim or encounter.
| Associated Code | Description | Typical Pairing Context | Bundling Risk |
|---|---|---|---|
| 66761 | Iridotomy/iridectomy by laser | Surgeon’s code for the primary procedure | No (different provider, different claim) |
| 66680 | Repair of iris, ciliary body | When iridectomy accompanies iris repair | No |
| 99100 | Qualifying circumstance — extreme age | Patient under 1 year or over 70 | No — add-on code |
| 99140 | Qualifying circumstance — emergency | Emergency anesthesia | No — add-on code |
| 99135 | Qualifying circumstance — controlled hypotension | When deliberate hypotension used | No — add-on code |
| 00144 | Anesthesia, corneal transplant | Combined procedure — use only if 00144 has higher base units | Yes — cannot bill both; use highest base unit code only |
| 00145 | Anesthesia, vitreoretinal surgery | Combined posterior segment procedure | Yes — cannot bill both; use highest base unit code only |
Which Code Combinations Trigger NCCI or CCI Edits?
- 00147 + 00144 or 00145 on the same claim by the same provider will be denied; only the single highest-valued anesthesia code is billable per the ASA and payer “one anesthesia code per session” rule
- 00147 + modifier 47 on the surgeon’s claim — if the surgeon reports modifier 47 on the surgical code, the anesthesiologist cannot separately bill 00147 for the same session; review documentation carefully
- Qualifying circumstance codes (99100, 99135, 99140) are not subject to NCCI bundling with 00147 and are appropriately billed as add-ons when documented
What Coding Errors Should You Avoid With CPT 00147?
The most common errors on 00147 claims are not definitional mistakes — they’re documentation and modifier omissions that are entirely preventable.
Top coding and billing errors with CPT 00147 (ranked by audit frequency):
- Missing or incorrect supervision modifier — Failing to append AA, QK, QX, QZ, or QY is the single most common denial cause for anesthesia claims with Medicare and most commercial payers.
- Absent physical status modifier — Many payers will reject or downcode claims without a P1–P6 modifier; it must be supported by the preanesthesia assessment.
- Incorrect anesthesia time calculation — Rounding errors or failing to document actual start/stop times creates discrepancies that trigger ADR (Additional Documentation Requests) during post-payment review.
- Reporting 00147 when a higher-base-unit eye code applies — If vitreoretinal surgery (00145, 6 base units) was performed during the same session, billing 00147 (4 base units) instead of 00145 results in underpayment.
- Billing 00147 when only topical/local anesthesia was administered — If the surgeon applied topical drops or administered a retrobulbar block without a separate anesthesia provider, 00147 is not billable.
- Using modifier 47 incorrectly — Modifier 47 is appended to the surgeon’s procedure code when the surgeon also provides general/regional anesthesia; it should not appear on a separately billed 00147 claim.
- Omitting qualifying circumstance codes when applicable — Forgetting to bill 99100 for elderly patients or 99140 for emergency anesthesia leaves legitimate revenue uncaptured.
What Do Auditors and RAC Reviewers Look for When Reviewing Claims With CPT 00147?
Anesthesia claims draw specific scrutiny in post-payment review for the following:
- Concurrent procedure time overlap — RAC reviewers check whether the same anesthesiologist billed for more than 4 concurrent cases simultaneously (which is prohibited under Medicare medical direction rules)
- Mismatch between surgical and anesthesia time — If the surgeon’s operative note documents a 20-minute procedure but the anesthesia record reflects 90 minutes of anesthesia time without explanation, expect an ADR
- Unsupported physical status — P3 or higher modifier claims without supporting comorbidities in the medical record are flagged for review
- Missing CRNA attestation — In medically directed cases, the anesthesiologist must document that all five TEFRA requirements were met; absent documentation triggers denial
How Does CPT 00147 Relate to Other CPT Codes?
Understanding where 00147 fits within the broader ophthalmic anesthesia and surgical coding landscape is essential for accurate claims construction.
| Related Code | Relationship Type | Key Distinction |
|---|---|---|
| 00140 | Parent/catch-all | Use 00140 only when no specific eye sub-code applies |
| 00142 | Sibling (same base units) | Lens surgery — cataract, IOL; not iris |
| 00144 | Sibling (higher base units) | Corneal transplant; supersedes 00147 in combined cases |
| 00145 | Sibling (higher base units) | Vitreoretinal; supersedes 00147 in combined cases |
| 00148 | Sibling (same base units) | Ophthalmoscopy/diagnostic; non-surgical |
| 66761 | Surgical code (surgeon bills) | The iridotomy/iridectomy procedure code; different claim, same encounter |
| 66680 | Surgical code (surgeon bills) | Iris/ciliary body repair; may accompany iridectomy |
| 99100 | Add-on/qualifying circumstance | Extreme age; billable in addition to 00147 |
What Is the Correct Code Sequencing or Reporting Order When CPT 00147 Appears With Other Codes?
- Report only one anesthesia procedure code per session — select the code with the highest base unit value when multiple surgical procedures are performed.
- Append the supervision/performing provider modifier (AA, QK, QX, QZ, or QY) directly to 00147 — this is not optional.
- Append the physical status modifier (P1–P6) as a second modifier on the same line item.
- Add qualifying circumstance codes (99100, 99135, 99140) as separate line items on the claim, not as modifiers on 00147.
- The surgeon’s procedure code (e.g., 66761) is reported on a separate claim by the operating surgeon — it does not appear on the anesthesia claim.
Real-World Coding Scenario — How CPT 00147 Is Applied in Practice
Clinical scenario: A 74-year-old patient with primary angle-closure glaucoma and controlled type 2 diabetes (ASA Physical Status P2) presents to an ambulatory surgery center for a surgical peripheral iridectomy (CPT 66761 reported by the ophthalmologist). A separate anesthesiologist provides monitored anesthesia care (MAC). Anesthesia start time is 9:04 AM; stop time is 9:47 AM — 43 minutes total.
Correct Code Application
- CPT 00147 — anesthesia for iridectomy (4 base units)
- Time units — 43 minutes ÷ 15 = 2.87, rounded to 3 time units (per payer rounding rules)
- Total units — 4 base + 3 time = 7 units
- Modifier AA — anesthesiologist personally performed service
- Modifier P2 — patient with mild systemic disease (controlled diabetes)
- CPT 99100 — qualifying circumstance for extreme age (patient is 74 years old, over 70)
- Claim submitted with 00147-AA-P2 as primary line; 99100 as secondary add-on line
Common Mistake in This Scenario
- Incorrect: Reporting 00147 with modifier P1 (normal healthy patient) — the documented diabetes and age qualify this patient for P2 and the 99100 add-on; omitting these leaves reimbursement on the table and misrepresents the patient’s clinical status
- Incorrect: Failing to append 99100 for the patient’s age — this qualifying circumstance code is frequently overlooked and represents a straightforward capture opportunity
- Incorrect: Billing 00148 (ophthalmoscopy) instead of 00147 — both carry 4 base units, but using the wrong code creates a CPT-to-diagnosis mismatch that can trigger denial when the ICD-10 code reflects glaucoma, not a diagnostic exam
Frequently Asked Questions About CPT Code 00147
Is CPT Code 00147 Still Valid for Use in 2025?
CPT code 00147 remains a valid, active code for anesthesia services rendered during iridectomy procedures in 2025, with no changes to its descriptor or base unit assignment. Coders should verify annually against the current AMA CPT Professional Edition and the CMS Physician Fee Schedule update to confirm that no revisions have been applied to the code’s coverage status or base unit value.
How Is Reimbursement Calculated for CPT 00147?
Reimbursement for CPT 00147 is calculated using the formula: (Base Units + Time Units) × Anesthesia Conversion Factor. With 4 base units and a typical 30-minute procedure generating 2 time units, a total of 6 units multiplied by a locality-specific Medicare conversion factor (approximately $22–$25 per unit nationally) yields an estimated Medicare payment of $132–$150. Commercial payer rates vary and should be confirmed against current contracted fee schedules.
What Is the Difference Between CPT 00147 and CPT 00140?
CPT 00140 is the “not otherwise specified” anesthesia code for eye procedures, while 00147 is procedure-specific to iridectomy. When an iridectomy is the documented surgical service, 00147 is the correct and more precise code — it should always be selected over 00140 for iridectomy cases. CPT 00140 carries 5 base units, making it actually worth more than 00147; however, it should only be used when no specific eye sub-code accurately describes the anesthetic event.
Which Modifier Is Required When a CRNA Performs Anesthesia for CPT 00147 Without Physician Direction?
When a CRNA independently performs anesthesia services without physician medical direction, modifier QZ must be appended to the claim. If the CRNA is working under medical direction from an anesthesiologist directing 2–4 concurrent cases, the CRNA’s claim uses modifier QX and the directing anesthesiologist’s claim uses modifier QK. Selecting the wrong supervision modifier is one of the most audited issues in anesthesia billing.
Can CPT 00147 and 00145 Both Be Billed When an Iridectomy and Vitreoretinal Procedure Are Performed Together?
No — when multiple surgical procedures are performed under a single anesthetic, only the anesthesia code with the highest base unit value is reported for the session. If both an iridectomy and a vitreoretinal procedure are performed, CPT 00145 (6 base units) supersedes CPT 00147 (4 base units) and is the only anesthesia code billed. The total anesthesia time for the combined session is reported with that single code.
What ICD-10 Codes Support Medical Necessity for CPT 00147?
Common ICD-10 diagnosis codes that support medical necessity for anesthesia during iridectomy include H40.20x (unspecified primary angle-closure glaucoma), H40.10x (unspecified open-angle glaucoma), H21.00 (idiopathic iris cysts), and Q13.2 (congenital iris abnormality). The diagnosis documented must reflect the clinical indication for both the iridectomy and the need for formal anesthesia services rather than topical or local anesthesia alone.
Key Takeaways for Billing and Coding CPT 00147
- CPT 00147 has 4 base units and covers anesthesia for iridectomy — always select the highest-base-unit eye anesthesia code when multiple concurrent eye procedures are performed under one anesthetic
- Reimbursement is time-driven: base units plus time units multiplied by a locality-specific anesthesia conversion factor — not a standard RVU-based fee schedule calculation
- Supervision and physical status modifiers are required on every 00147 claim; missing either is a leading cause of denial and audit exposure
- Qualifying circumstance add-on codes (99100 for extreme age, 99140 for emergency) are frequently underbilled — document and capture them when clinically supported
- Only one anesthesia code per session — if 00144 or 00145 applies to a concurrent procedure with higher base units, those codes replace 00147
- Topical/local anesthesia by the surgeon alone does not support a separate 00147 claim — a qualified anesthesia provider must be separately documented and present
- Verify anesthesia time documentation accuracy before submission — time discrepancies between the surgical and anesthesia records trigger ADR and post-payment review
For current reimbursement rates, consult the CMS Physician Fee Schedule lookup tool and the CMS Medicare Claims Processing Manual, Chapter 12, Section 50 for complete anesthesia billing guidelines. The AMA CPT code set and CMS National Correct Coding Initiative (NCCI) edits should be reviewed regularly to confirm code relationships and bundling rules.
