2026 ICD-10-CM Diagnosis Code H18.231Secondary corneal edema, right eye

ICD-10-CM Codes›H00–H59›H15-H22›H18

ICD-10-CM H18.231
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H18.231 is a billable ICD-10-CM diagnosis code for secondary corneal edema, right eye. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 124 through 125. Coders also document this condition as corneal infiltrate of right eye following penetrating keratoplasty. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease.

Code Identity

ICD-10-CM Code
H18.231
Billable Status
Yes — Valid for Submission
Code Describes
Secondary corneal edema, right eye
Short Description
Secondary corneal edema, right eye
Same as the full description in the CMS dataset.
Parent Code
H18.23
Secondary corneal edema

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH15-H22Disorders of sclera, cornea, iris and ciliary body
CategoryH18Other disorders of cornea
This CodeH18.231Secondary corneal edema, right eye

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Corneal infiltrate of right eye following penetrating keratoplasty
  • Infiltrate of cornea following laser assisted in situ keratomileusis
  • Infiltrate of cornea of right eye
  • Infiltrate of cornea of right eye following laser assisted in situ keratomileusis of right eye

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR EYE001
Cornea and external disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Corneal Disorders

Your cornea is the outermost layer of your eye. It is clear and shaped like a dome. The cornea helps to shield the rest of the eye from germs, dust, and other harmful matter. It also helps your eye to focus. If you wear contact lenses, they float on top of your corneas.

Read the full article at MedlinePlus

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Convert H18.231 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
371.22 Secondary corneal edema
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About H18.231Overview

Is H18.231 (Secondary corneal edema) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report secondary corneal edema, right eye on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does H18.231 group to?

When secondary corneal edema, right eye is the principal diagnosis on an inpatient stay, it groups to MS-DRG 124, 125, with relative weights from 0.7678 to 1.3231 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of H18.231?

Under the General Equivalence Mappings, secondary corneal edema, right eye converts to ICD-9-CM 371.22 (secondary corneal edema). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.