H31.121 ICD-10-CM Code: Diffuse secondary atrophy of choroid, right eye
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the eye and adnexa (H00-H59) / Disorders of choroid and retina (H30-H36)
H31.121
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceDiffuse secondary atrophy of choroid, right eye
Widespread thinning and wasting of the choroid layer in the right eye that has developed as a secondary consequence of another eye condition or disease.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for H31.121 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for H31.121 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for H31.121 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for H31.121 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for H31.121 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for H31.121 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for H31.121 in this effective period.
Buddy Documentation Tip
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 H31.121 an HCC code?
No. H31.121 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- H31.121
- Description
- Diffuse secondary atrophy of choroid, right eye
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
H31.121 is the ICD-10-CM diagnosis code for diffuse secondary atrophy of choroid, right eye. Widespread thinning and wasting of the choroid layer in the right eye that has developed as a secondary consequence of another eye condition or disease. H31.121 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of choroid and retina (h30-h36).
H31.121 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.
Identify and document the underlying condition causing the secondary atrophy when possible.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for H31.121 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Identify and document the underlying condition causing the secondary atrophy when possible
- •Distinguish this from age-related atrophy (H31.11x) by confirming it is secondary to another condition