2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H18.20 is a billable ICD-10-CM diagnosis code for unspecified corneal edema. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H18.20: its own notes plus those printed at Chapter 7. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury (trauma) of eye and orbit (S05.-)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)

Notes

General instructions on how these codes are used.

From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • Use an external cause code following the code for the eye condition, if applicable, to identify the cause of the eye condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

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

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About H18.20Overview

What is the ICD-10 code for unspecified corneal edema?

The ICD-10-CM code for unspecified corneal edema is H18.20 (sometimes written as H1820). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

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 125, 124, with relative weights from 0.7699 to 1.2470 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.