H18.40 ICD-10-CM Code: Unspecified corneal degeneration
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the eye and adnexa (H00-H59) / Disorders of sclera, cornea, iris and ciliary body (H15-H22)
H18.40
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceUnspecified corneal degeneration
Degeneration or deterioration of the cornea that cannot be classified into a more specific type.
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 H18.40 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for H18.40 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for H18.40 in this effective period.
Excludes 1
Official- Mooren's ulcer (H16.0-)
- recurrent erosion of cornea (H18.83-)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for H18.40 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for H18.40 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for H18.40 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 H18.40 an HCC code?
No. H18.40 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- H18.40
- Description
- Unspecified corneal degeneration
- 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
H18.40 is the ICD-10-CM diagnosis code for unspecified corneal degeneration. Degeneration or deterioration of the cornea that cannot be classified into a more specific type. H18.40 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).
H18.40 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.
Use this code only when the specific type of corneal degeneration is not documented.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for H18.40 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.