2026 ICD-10-CM Diagnosis Code H05.129Orbital myositis, unspecified orbit

ICD-10-CM Codes›H00–H59›H00-H05›H05

ICD-10-CM H05.129
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H05.129 is a billable ICD-10-CM diagnosis code for orbital myositis, unspecified orbit. 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 acute inflammation of orbit. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Oculofacial plastics and orbital conditions.

Code Identity

ICD-10-CM Code
H05.129
Billable Status
Yes — Valid for Submission
Code Describes
Orbital myositis, unspecified orbit
Short Description
Orbital myositis, unspecified orbit
Same as the full description in the CMS dataset.
Parent Code
H05.12
Orbital myositis

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH00-H05Disorders of eyelid, lacrimal system and orbit
CategoryH05Disorders of orbit
This CodeH05.129Orbital myositis, unspecified orbit

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute inflammation of orbit
  • Acute orbital myositis
  • Chronic inflammation of orbit
  • Chronic orbital myositis
  • Extraocular myositis
  • Fibromyositis
  • Inflammatory pseudotumor of orbit
  • Myositic orbital pseudotumor
  • Orbital myositis

Clinical ClassificationClinical

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

CCSR EYE008
Oculofacial plastics and orbital conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Orbital Myositis

    inflammation of the extraocular muscle of the eye. it is characterized by swelling which can lead to ischemia, fibrosis, or orbital pseudotumor.

  • Orbital Pseudotumor

    a nonspecific tumor-like inflammatory lesion in the orbit of the eye. it is usually composed of mature lymphocytes; plasma cells; macrophages; leukocytes with varying degrees of fibrosis. orbital pseudotumors are often associated with inflammation of the extraocular muscles (orbital myositis) or inflammation of the lacrimal glands (dacryoadenitis).

  • Fibromyositis

    inflammation and fibrous degeneration of a muscle.

  • Orbital Myositis

    a rare form of myositis that affects only the orbital muscles.

Patient EducationClinical

Eye Diseases

Even if your eyes feel healthy, you could have a problem and not know it. That's why regular eye exams are so important. Refractive errors are the most common type of vision problem that makes it hard to see clearly. But some eye conditions or diseases don't have any symptoms and can lead to a permanent loss of vision.

The full article covers:

  • What diseases can affect the eye?
  • What are the symptoms of eye diseases?
  • Who is more likely to develop eye diseases?
  • What are the treatments for eye diseases?
  • Can eye diseases be prevented?

Read the full article at MedlinePlus

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

Convert H05.129 to ICD-9-CMHistory

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

ICD-9-CM
376.12 Orbital myositis
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 H05.129Overview

Is H05.129 (Orbital myositis) a billable code?

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

What MS-DRG does H05.129 group to?

When orbital myositis, unspecified orbit 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 H05.129?

Under the General Equivalence Mappings, orbital myositis, unspecified orbit converts to ICD-9-CM 376.12 (orbital myositis). 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.