CPT Code 00142: Anesthesia for lens surgery billing guide

Key Takeaways

CPT Code 00142 describes anesthesia for lens surgery (including cataract surgery), updated January 1, 2026 with a revised short and medium descriptor.

Base units differ by payer: Medicare assigns 4 base units; the ASA Relative Value Guide assigns 6 units for commercial insurers.

MAC billing under 00142 requires documented medical necessity per CMS Article A57361 – it is not automatically reimbursable.

Pabau’s claims management software helps anesthesia practices track modifier requirements, document medical necessity, and reduce claim denials.

CPT Code 00142 is the anesthesia code for lens surgery, covering cataract extraction and lens replacement procedures. Most denials on this code result from a missing or misapplied anesthesia modifier rather than an incorrect diagnosis code.

CPT Code 00142: definition and updated 2026 description

The code sits in the Eye subsection of the CPT anesthesia codes (00140-00148), which covers procedures on the eye. Effective January 1, 2026, the American Medical Association (AMA) updated the short and medium descriptors for CPT Code 00142.

The current short descriptor reads “Anesth, lens surgery,” and the medium descriptor specifies “Anesthesia for procedures on the eye; lens surgery.”

This guide covers the billing essentials: base unit values, applicable modifiers, ICD-10 pairings, monitored anesthesia care (MAC) requirements, reimbursement differences across payers, and the most common denial scenarios anesthesia billing teams encounter with this code.

Base units and reimbursement for CPT Code 00142

Anesthesia billing uses a formula rather than a flat fee: Total units = Base units + Time units + Qualifying circumstance units. The reimbursement then equals total units multiplied by the payer’s anesthesia conversion factor. For CPT Code 00142, base unit values split depending on who is paying.

Medicare assigns 4 base units to CPT Code 00142. The American Society of Anesthesiologists (ASA) Relative Value Guide (RVG) assigns 6 base units for commercial payers.

That 2-unit difference is meaningful: with a typical Medicare conversion factor of roughly $21-$22 per unit (varying by geography and year per the CMS Anesthesiologists Center), the difference represents approximately $40-$45 in base-unit reimbursement alone before time units are added.

How time units are calculated

Time units are added at a rate of 1 unit per 15-minute interval of anesthesia time (Medicare standard) or per the payer’s contracted interval. Cataract surgery typically takes 15-30 minutes under anesthesia, so most claims for CPT Code 00142 will include 1-2 time units in addition to base units.

Physical status modifiers (P1-P6) are added on top of base and time units for certain payers. A P3 modifier (patient with severe systemic disease) adds 1 qualifying unit under ASA guidelines; P4 adds 2.

Medicare does not separately reimburse physical status modifiers, but documentation of physical status is still required for record integrity. Anesthesia practices using claims management software can automate unit calculations and flag missing modifier fields before submission.

Reimbursement variation by geography and payer

The CMS Physician Fee Schedule lookup tool allows practices to verify the exact conversion factor applicable to their locality before submitting CPT Code 00142 claims. Commercial payer rates vary further based on contracted rates.

State fee schedules also differ: Arizona’s Industrial Commission, for instance, publishes its own anesthesia fee schedule with per-unit amounts that differ from the Medicare national rate. Always verify with each payer contract before estimating reimbursement.

Modifiers for CPT Code 00142

Modifiers tell payers who performed the anesthesia and under what conditions. For CPT Code 00142, applying the wrong modifier – or omitting one entirely – is one of the fastest routes to a CARC B7 denial.

• AA: Anesthesia services personally performed by the anesthesiologist. This is the standard modifier for a physician anesthesiologist who is physically present and performing all anesthesia care during lens surgery.
• QY: Medical direction of one qualified CRNA or Anesthesiologist Assistant (AA) by an anesthesiologist. Applies when the anesthesiologist directs exactly one concurrent case, as distinct from QK, which covers two to four concurrent cases.
• QZ: CRNA (Certified Registered Nurse Anesthetist) providing anesthesia services without physician supervision. Used when the CRNA operates independently, as permitted by state law and facility policy.
• QX: CRNA providing anesthesia under the medical direction of a physician. The physician must be present for induction, available throughout, and perform specific oversight tasks to qualify for medical direction billing.
• QK: Medical direction of two, three, or four concurrent anesthesia procedures involving a CRNA or AA (Anesthesiologist Assistant).
• AD: Medical supervision by a physician (more than four concurrent procedures). Reimbursement is limited to three base units per procedure under this modifier.
• P1-P6: Physical status modifiers appended after the supervision/role modifier to indicate patient health status. Payers vary on whether these affect reimbursement.
• 99100: Qualifying circumstance code for anesthesia on a patient under age 1 or over age 70. Appended when age qualifies as an additional risk factor; adds 1 unit in ASA RVG billing.

The QX vs QZ distinction is state-law dependent. In states that have opted out of Medicare’s physician supervision requirement for CRNAs, QZ applies even in hospital settings.

Billing teams should verify the opt-out status of their state and confirm each facility’s credentialing policies before applying either modifier. The ASA’s Anesthesia Payment Basics Series provides detailed guidance on modifier selection for supervision scenarios.

ICD-10 codes commonly paired with CPT Code 00142

Accurate ICD-10 code linkage is a medical necessity requirement. Pairing CPT Code 00142 with an unrelated or insufficiently specific diagnosis code is a leading cause of claim rejection.

Additional cataract-adjacent diagnoses pair with CPT Code 00142 less often but still come up: ICD-10 Code H26.8 (other specified cataract) covers presentations not captured by the age-related codes. ICD-10 Code H25.9 (unspecified age-related cataract) is the fallback when laterality has not yet been documented.

Laterality matters. H25.11 (right eye) and H25.12 (left eye) are not interchangeable – submitting the wrong laterality code is one of the more common clerical errors that generates a denial requiring appeal.

For ICD-10 diagnostic code pairing accuracy across specialties, building a payer-specific crosswalk into your billing workflow is worth the upfront investment. The same specificity principle applies to ICD-10 Code H26.9 (unspecified cataract). Using it in place of a laterality-specific code without documented justification invites the same medical necessity scrutiny as a laterality mismatch.

Monitored anesthesia care and CPT Code 00142

Cataract surgery is commonly performed under topical or local anesthesia without the involvement of an anesthesia professional. MAC (Monitored Anesthesia Care) under CPT Code 00142 is not automatically billable for lens surgery – medical necessity must be documented and supported by qualifying diagnoses.

CMS Article A57361 governs MAC medical necessity for procedures that do not inherently require anesthesia professional services. Qualifying conditions that support MAC billing under CPT Code 00142 include significant anxiety disorder, uncontrolled movement disorders, severe cardiac or pulmonary disease, developmental disability, and other documented conditions where patient safety requires the presence of anesthesia personnel.

The qualifying ICD-10 code must appear on the claim alongside the primary procedure diagnosis. Per CMS Billing and Coding Article A57361, the QS modifier must also be appended to the claim whenever monitored anesthesia care is billed.

MAC documentation requirements

Pre-operative documentation must clearly state the medical reason MAC is necessary for this specific patient. A generic “patient preference” note does not meet the threshold. The anesthesia record should document:

• The qualifying condition (e.g., severe anxiety disorder, movement disorder, extreme age with comorbidities)
• Pre-operative evaluation findings that support MAC over topical anesthesia
• Patient ASA physical status classification
• Monitoring details (EKG, pulse oximetry, BP at minimum)
• Start and stop times for anesthesia service

Practices that use digital intake forms can standardize pre-operative MAC justification fields so missing documentation is caught before the procedure, not discovered at claims review. Missing a single qualifying field in the pre-op note is enough for a payer to deny the MAC charge.

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Medicare vs commercial payer reimbursement for CPT 00142

The base unit discrepancy between Medicare (4 units) and commercial payers following the ASA RVG (6 units) creates two parallel billing tracks that anesthesia practices must manage simultaneously. The difference extends beyond base units.

• Medicare: 4 base units, 1 unit per 15 minutes of time, no separate physical status payment, anesthesia conversion factor set annually by CMS locality. Billed on CMS-1500 for physician anesthesiologists and CRNAs; UB-04 for hospital-employed anesthesia services.
• Commercial/ASA RVG: 6 base units, time units per contracted interval (may differ from 15 minutes), physical status modifiers may add qualifying units, conversion factor per contracted rate. Some commercial payers align their fee schedules to ASA RVG; others use their own contracted rates.
• Medicaid: Varies by state. California Medi-Cal, for example, publishes its own anesthesia base unit table which may differ from both Medicare and ASA RVG values. Verify directly with the state’s published fee schedule.
• Workers’ compensation: State-specific. Arizona’s Industrial Commission publishes an annual anesthesia fee schedule with per-unit dollar amounts that may differ from Medicare rates.

Always apply the payer-specific base unit count when calculating expected reimbursement. Using Medicare’s 4-unit figure on a commercial claim undervalues the service and may result in accepted underpayment.

Using ASA RVG’s 6 units on a Medicare claim may trigger an overpayment recovery request. Verify payer-specific base unit tables annually, since CPT code values and the ASA RVG are both updated each year.

For practices handling a volume of CPT Code 00142 claims, automated billing workflows that route claims by payer type can reduce the manual step of verifying which base unit count applies. Practices managing multiple payer contracts will benefit from billing rule sets per payer class built into their workflow.

Documentation requirements and denial prevention for CPT 00142

CARC B7 is the denial reason code for “this provider was not certified/eligible to be paid for this procedure/service on this date of service.” It appears frequently on CPT Code 00142 claims when modifier documentation doesn’t match the anesthesia supervision arrangement documented for that date of service, or when a CRNA bills without confirming payer enrollment status.

Common denial reasons for CPT Code 00142 claims

• CARC B7: Provider not certified or eligible. Usually triggered by QX/QZ modifier mismatch, lapsed CRNA enrollment, or billing under the wrong provider NPI.
• Medical necessity denial: MAC claim lacks qualifying ICD-10 code or pre-operative documentation of the medical condition requiring anesthesia professional services.
• Modifier missing or incorrect: Claim submitted without an anesthesia role modifier (AA, QX, QZ, QK) – payer cannot determine who provided the service.
• Laterality error: ICD-10 code does not match the eye operated on (H25.11 submitted for left eye procedure).
• Time unit calculation error: Anesthesia start and stop times not documented or inconsistent with time units billed.
• Duplicate claim: Concurrent billing of CPT 00142 and 66984 (the cataract surgery surgical code) by an anesthesia group without payer-specific authorization to bill both. This practice is payer-specific and not standard; verify before attempting.

Denial management for CPT Code 00142 follows the same structured appeal process as other anesthesia codes: identify the CARC, pull the anesthesia record, verify that modifier and documentation match, and resubmit with a corrected claim or a written appeal with supporting documentation.

Practices managing high volumes of eye surgery anesthesia claims can apply the same CARC-based denial-prevention framework used for other procedure categories, such as CPT Code 97014.

Billing workflow for CPT Code 00142

A clean submission workflow for CPT Code 00142 typically follows these steps:

1. Confirm the lens procedure being performed and identify the primary surgical CPT code (e.g., 66984 for cataract extraction with IOL insertion).
2. Document ASA physical status and confirm MAC medical necessity if applicable, referencing qualifying ICD-10 codes.
3. Record anesthesia start and stop times in the intraoperative record.
4. Assign the correct supervision modifier (AA, QK, QX, or QZ) based on the supervision arrangement in place and state law.
5. Apply physical status modifier (P1-P6) as required by the payer.
6. Apply qualifying circumstance code 99100 if the patient is under 1 or over 70 years of age and the payer recognizes it.
7. Calculate total units: base units (4 for Medicare, 6 for commercial/ASA) + time units + qualifying circumstance units.
8. Submit on CMS-1500 (professional services) or UB-04 (facility/hospital billing) per the provider’s enrollment type.

HIPAA-compliant documentation practices at each step create the audit trail needed to defend claims on appeal. Practices looking to reduce pre-submission errors can implement HIPAA-compliant documentation practices as part of their anesthesia billing workflow.

Related anesthesia CPT codes for eye procedures

CPT Code 00142 sits within the 00140-00148 eye anesthesia code family. Selecting the correct code for the specific ophthalmic procedure matters: using 00142 for a vitreoretinal procedure, for instance, may be challenged as an incorrect code selection.

Corneal transplant procedures billed under CPT 00144 commonly pair with corneal diagnoses such as ICD-10 Code H18.10 (bullous keratopathy) or ICD-10 Code H17.9 (corneal scar and opacity), while iridectomy under CPT 00147 pairs with iris and ciliary body disorders such as ICD-10 Code H22.

CPT 00140 (“not otherwise specified”) is the fallback for procedures not explicitly described by the more specific codes in this family. Its Medicare base unit value of 5 is higher than 00142’s 4 units, a result that reflects historical RVU assignment methodology rather than clinical complexity.

For surgical coding teams building procedure-to-anesthesia crosswalks, similar code-family structures apply in other specialties: IVF CPT codes for surgical procedures, for example, also involve separate anesthesia codes that must be paired correctly with the primary procedure code.

The same base-unit logic that separates 00142 from 00144 and 00147 also shows up in other anesthesia guides, such as CPT Code 01502 (lower leg embolectomy anesthesia) and CPT Code 00120 (ear surgery anesthesia).

When building your CPT code library, cross-referencing anesthesia codes with their surgical counterparts helps prevent mismatches. Teams managing diverse procedure types across specialties will find structured CPT codes for healthcare coaching services and other specialty code libraries useful reference points for understanding how base unit logic is applied across the CPT anesthesia section.

For structured anesthesia coding guidance and annual updates to the RVG, refer to the ASA’s Anesthesia Payment Basics coding resources.

Conclusion

The base unit difference between Medicare and commercial payers, the MAC medical necessity threshold, and the QX vs QZ modifier distinction are where most CPT Code 00142 claims break down. Getting these right requires documentation precision at every step of the anesthesia encounter, from the pre-operative note through claim submission.

Pabau’s billing automation platform helps anesthesia and surgical practices build modifier requirements into their billing workflows, standardize pre-operative MAC documentation, and track denial patterns by CARC code. To see how Pabau handles billing documentation for procedure-based practices, book a demo with the team.

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