2026 ICD-10-CM Diagnosis Code H18.20Unspecified corneal edema

ICD-10-CM Codes›H00–H59›H15-H22›H18

ICD-10-CM H18.20
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H18.20 is a billable ICD-10-CM diagnosis code for unspecified corneal edema. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease.

Code Identity

ICD-10-CM Code
H18.20
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified corneal edema
Short Description
Unspecified corneal edema
Same as the full description in the CMS dataset.
Parent Code
H18.2
Other and unspecified 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 CodeH18.20Unspecified corneal edema

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral edema of corneal stroma of eyes
  • Bilateral microcystic edema of cornea
  • Bullous corneal epithelial edema
  • Corneal edema
  • Corneal epithelial edema
  • Corneal stromal edema
  • Disorder of cornea following cataract surgery
  • Edema of cornea of bilateral eyes
  • Edema of cornea of left eye
  • Edema of cornea of right eye
  • Edema of corneal stroma of left eye
  • Edema of corneal stroma of right eye
  • Infiltrate of cornea
  • Infiltrate of cornea of bilateral eyes
  • Infiltrate of cornea of left eye
  • Infiltrate of cornea of right eye
  • Microcystic corneal edema
  • Microcystic edema of cornea of left eye
  • Microcystic edema of cornea of right eye
  • Pseudophakic corneal edema

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

Clinical InformationClinical

  • Corneal Edema

    an excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.

  • Corneal Edema

    hazy, swollen cornea.

  • Microcystic Corneal Edema|Microcystic Edema|Microcytic Corneal Edema

    corneal edema of inflammatory origin associated with contact lens wear and morphologically characterized by presence of epithelial microcysts. microcysts are small (typically 10-50 microns in diameter), clear, irregularly shaped high refractive inclusions that form in the basal layers of the epithelium and move towards the anterior surface of the cornea, surrounding epithelial haze. the cause of microcytic edema is related to the physical presence of contact lenses and possibly a mechanical effect of lens wear.

  • Stromal Corneal Edema|Corneal Stromal Edema

    fluid from the aqueous humor enters the corneal stroma and causes swelling.

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

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert H18.20 to ICD-9-CMHistory

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

ICD-9-CM
371.20 Corneal edema NOS
Exact Match The mapping is direct, with no qualifiers.

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 H18.20Overview

Is H18.20 (Other and unspecified corneal edema) a billable code?

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

What MS-DRG does H18.20 group to?

When unspecified corneal edema 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 H18.20?

Under the General Equivalence Mappings, unspecified corneal edema converts to ICD-9-CM 371.20 (corneal edema NOS). The mapping is a direct match.

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.