Question 1

What is ICD-10 code H21.242?

Accepted Answer

H21.242 is the ICD-10-CM diagnosis code for degeneration of pupillary margin, left eye. Deterioration of the pupillary margin (the edge of the pupil opening) in the left eye, which may affect pupil function and appearance. H21.242 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).

H21.242 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.

This code is specific to the left eye; use H21.241 for right eye or H21.243 for bilateral involvement.

Question 2

Is H21.242 an HCC code?

Accepted Answer

No. H21.242 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 H21.242 billable?

Accepted Answer

Yes. H21.242 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. H21.242 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

What is the V28 vs V24 difference for H21.242?

Accepted Answer

H21.242 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 model rewards H21.242 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting H21.242?

Accepted Answer

This code is specific to the left eye; use H21.241 for right eye or H21.243 for bilateral involvement Ensure documentation clearly indicates left eye involvement to avoid coding errors

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H21.242

Is H21.242 an HCC code?

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H21.242 ICD-10-CM Code: Degeneration of pupillary margin, left eye

HCC Buddy Code Card

H21.242

Is H21.242 an HCC code?

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Open H21.242 in the Interactive Encoder