Question 1

What is ICD-10 code H21.511?

Accepted Answer

H21.511 is the ICD-10-CM diagnosis code for anterior synechiae (iris), right eye. Scar tissue adhesion between the iris and the cornea (front of the eye) in the right eye. This restricts the iris from moving normally and can affect vision and eye pressure. H21.511 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of sclera, cornea, iris and ciliary body (h15-h22).

H21.511 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Verify documentation specifies anterior synechiae and right eye involvement.

Question 2

Is H21.511 an HCC code?

Accepted Answer

No. H21.511 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is H21.511 billable?

Accepted Answer

Yes. H21.511 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. H21.511 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

Which HCC does H21.511 map to under V28?

Accepted Answer

H21.511 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

Question 5

What does H21.511 pay in RAF?

Accepted Answer

H21.511 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

Question 6

What is the V28 vs V24 difference for H21.511?

Accepted Answer

H21.511 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither community model rewards H21.511 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's V28/V24 community RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a community payment HCC.

Question 7

What documentation supports H21.511?

Accepted Answer

Verify documentation specifies anterior synechiae and right eye involvement Document the underlying cause (uveitis, trauma, surgery) if present for complete clinical picture H21.511 is not a CMS-HCC payment code, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

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H21.511

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H21.511 ICD-10-CM Code: Anterior synechiae (iris), right eye

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H21.511

Is H21.511 an HCC code?

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Child Codes

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Work H21.511 in HCC Buddy