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T86.8429 ICD-10-CM Code: Corneal transplant infection, unspecified eye

T86.8429 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

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FY 2026 Apr update / Injury, poisoning and certain other consequences of external causes (S00-T88) / Complications of surgical and medical care, not elsewhere classified (T80-T88)

T86.8429

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Corneal transplant infection, unspecified eye

An infection has developed in a cornea transplant, but the specific eye affected is not documented.

Buddy the Bee presenting code insight

Buddy Insight

Unspecified eye corneal transplant infection indicates a documented infection complication where laterality is not specified or determinable.

CMS-HCC V28

N/A

—

Not mapped

CMS-HCC V24

HCC 176

RAF 0.582

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

HCC 176

RAF 0.000

RXHCC

N/A

—

Not mapped

Code Book Path

Official
T86.84Complications of corneal transplant
T86.842Corneal transplant infection
T86.8429Corneal transplant infection, unspecified eye

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for T86.8429 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for T86.8429 in this effective period.

Related Child Codes

Official
T86.8421Corneal transplant infection, right eye
T86.8422Corneal transplant infection, left eye
T86.8423Corneal transplant infection, bilateral

Includes

Official

ICD-10-CM does not list Includes notes for T86.8429 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for T86.8429 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for T86.8429 in this effective period.

Use Additional

Official
  • code to specify infection

Code Also

Official

ICD-10-CM does not list Code Also instructions for T86.8429 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of corneal transplant procedure
Clinical evidence of corneal infection
Ophthalmologic examination findings
Rationale for unspecified laterality (bilateral involvement, unclear documentation)

MEAT Support

HCC Buddy guidance
Documentation of corneal transplant procedure
Clinical evidence of corneal infection
Ophthalmologic examination findings
Rationale for unspecified laterality (bilateral involvement, unclear documentation)

Audit Caution

HCC Buddy guidance
Using when laterality is documented elsewhere in the record
Not querying provider for laterality specification
Applying to bilateral infections inappropriately
Using for routine post-transplant follow-up without infection

Common Mistakes

HCC Buddy guidance
T86.8421 — corneal transplant infection, right eye (unspecified vs specified right)
T86.8422 — corneal transplant infection, left eye (unspecified vs specified left)
T86.8423 — corneal transplant infection, bilateral (unspecified vs bilateral)
Z94.7 — corneal transplant status (infection vs stable status)

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is T86.8429 an HCC code?

Yes. T86.8429 maps to Complications of Specified Implanted Device or Graft under the V24 model but is not retained in V28.

Code
T86.8429
Description
Corneal transplant infection, unspecified eye
HCC (V28)
No CMS-HCC V28 mapping
RAF
—
Billable
Yes
Payment year
2026

HCC Category Mapping

V24HCC 176, Complications of Specified Implanted Device or Graft
0.582
ESRDHCC 176, Complications of Specified Implanted Device or Graft
0.000

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work T86.8429 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for T86.8429

For T86.8429 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed T86.8429 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

T86.8429 is the ICD-10-CM diagnosis code for corneal transplant infection, unspecified eye. An infection has developed in a cornea transplant, but the specific eye affected is not documented. T86.8429 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering complications of surgical and medical care, not elsewhere classified (t80-t88).

Under the older CMS-HCC V24 model, T86.8429 maps to Complications of Specified Implanted Device or Graft (HCC 176) with a community, non-dual, aged base RAF weight of 0.582. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code only when laterality is not specified in the medical record. Because T86.8429 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for T86.8429 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Use this code only when laterality is not specified in the medical record
  • •Query the provider to clarify which eye is affected for more accurate coding

Clinical Significance

Unspecified eye corneal transplant infection indicates a documented infection complication where laterality is not specified or determinable. This diagnosis still represents a serious vision-threatening condition requiring prompt ophthalmologic intervention.

Documentation Requirements

  • ✓Documentation of corneal transplant procedure
  • ✓Clinical evidence of corneal infection
  • ✓Ophthalmologic examination findings
  • ✓Rationale for unspecified laterality (bilateral involvement, unclear documentation)
  • ✓Treatment plan for infection management
  • ✓Visual symptoms and examination findings
  • ✓Provider assessment confirming transplant-related infection
  • ✓Follow-up plans for laterality determination if possible

Commonly Confused Codes

  • •T86.8421: corneal transplant infection, right eye (unspecified vs specified right)
  • •T86.8422: corneal transplant infection, left eye (unspecified vs specified left)
  • •T86.8423: corneal transplant infection, bilateral (unspecified vs bilateral)
  • •Z94.7: corneal transplant status (infection vs stable status)
  • •H16.9: keratitis unspecified (transplant-related vs general keratitis)

Child Codes

T86.8421Corneal transplant infection, right eye
T86.8422Corneal transplant infection, left eye
T86.8423Corneal transplant infection, bilateral
T86.8429Corneal transplant infection, unspecified eye

Code Hierarchy

└T86Complications of transplanted organs and tissue└T86.8Complications of other transplanted organs and tissues└T86.84Complications of corneal transplant└T86.842Corneal transplant infection└T86.8429Corneal transplant infection, unspecified eye
└T86.8429Corneal transplant infection, unspecified eye

T86.8429 code history

Code setChange
FY2021 (effective Oct 1, 2020)Added to the code set

Source: official CMS ICD-10-CM order and addenda files, FY2016 through FY2027.

Because T86.8429 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

More on T86.8429

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