2026 ICD-10-CM Diagnosis Code H40.001Preglaucoma, unspecified, right eye

ICD-10-CM Codes›H00–H59›H40-H42›H40

ICD-10-CM H40.001
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H40.001 is a billable ICD-10-CM diagnosis code for preglaucoma, unspecified, 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 angle closure glaucoma suspect. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Glaucoma.

Code Identity

ICD-10-CM Code
H40.001
Billable Status
Yes — Valid for Submission
Code Describes
Preglaucoma, unspecified, right eye
Short Description
Preglaucoma, unspecified, right eye
Same as the full description in the CMS dataset.
Parent Code
H40.00
Preglaucoma, unspecified

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH40-H42Glaucoma
CategoryH40Glaucoma
This CodeH40.001Preglaucoma, unspecified, right eye

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Angle closure glaucoma suspect
  • Angle closure glaucoma suspect of right eye
  • Glaucoma suspect caused by corticosteroid
  • Glaucoma suspect of right eye
  • Glaucoma suspect of right eye caused by corticosteroid
  • Open angle glaucoma suspect
  • Open angle glaucoma suspect of right eye
  • Suspected glaucoma of right eye

Clinical ClassificationClinical

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

CCSR EYE003
Glaucoma
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Glaucoma

Glaucoma is a group of diseases that can damage the optic nerve of one, or both, of your eyes. This can result in vision loss. There are different types of glaucoma, but the most common type is open-angle glaucoma. Other less common types include angle-closure glaucoma, and congenital glaucoma.

The full article covers:

  • What is glaucoma?
  • What causes glaucoma?
  • What are the symptoms of glaucoma?
  • How is glaucoma diagnosed?
  • What are the treatments for glaucoma?
  • Can glaucoma be prevented?

Read the full article at MedlinePlus

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

Convert H40.001 to ICD-9-CMHistory

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

ICD-9-CM
365.00 Preglaucoma NOS
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 H40.001Overview

Is H40.001 (Preglaucoma, unspecified) a billable code?

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

What MS-DRG does H40.001 group to?

When preglaucoma, unspecified, 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 H40.001?

Under the General Equivalence Mappings, preglaucoma, unspecified, right eye converts to ICD-9-CM 365.00 (preglaucoma NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.