2027 ICD-10-CM Diagnosis Code H16.042Marginal corneal ulcer, left eye

ICD-10-CM Codes›H00–H59›H15-H22›H16

ICD-10-CM H16.042
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H16.042 is a billable ICD-10-CM diagnosis code for marginal corneal ulcer, left eye. 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. Coders also document this condition as marginal corneal ulcer of left eye. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease.

Code Identity

ICD-10-CM Code
H16.042
Billable Status
Yes — Valid for Submission
Code Describes
Marginal corneal ulcer, left eye
Short Description
Marginal corneal ulcer, left eye
Same as the full description in the CMS dataset.
Parent Code
H16.04
Marginal corneal ulcer

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH15-H22Disorders of sclera, cornea, iris and ciliary body
CategoryH16Keratitis
This CodeH16.042Marginal corneal ulcer, left eye

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Marginal corneal ulcer of left eye
  • Peripheral ulcerative keratitis
  • Peripheral ulcerative keratitis of left eye

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H16.042: 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.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name H16.042, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming H16.042: they are not reported together with it, unless the two conditions are unrelated.

  • H18.4 Corneal degeneration
    Mooren's ulcer (H16.0-) names H16.0-, which includes this code

Use Additional Code 1

These codes say to use an additional code from the note, and H16.042 is one of the codes named.

  • L51 Erythema multiforme
    corneal ulcer (H16.0-) names H16.0-, which includes this code

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 Ulcer

    loss of epithelial tissue from the surface of the cornea due to progressive erosion and necrosis of the tissue; usually caused by bacterial, fungal, or viral infection.

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 H16.042 to ICD-9-CMHistory

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

ICD-9-CM
370.01 Marginal corneal ulcer
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About H16.042Overview

What is the ICD-10 code for marginal corneal ulcer, left eye?

The ICD-10-CM code for marginal corneal ulcer, left eye is H16.042 (sometimes written as H16042). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is H16.042 (Marginal corneal ulcer) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report marginal corneal ulcer, left eye on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does H16.042 group to?

When marginal corneal ulcer, left eye 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 H16.042?

Under the General Equivalence Mappings, marginal corneal ulcer, left eye converts to ICD-9-CM 370.01 (marginal corneal ulcer). The mapping is approximate, so confirm the match fits the documentation.