2026 ICD-10-CM Diagnosis Code S04.02XAInjury of optic chiasm, initial encounter

ICD-10-CM Codes›S00–T88›S00-S09›S04

ICD-10-CM S04.02XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S04.02XA is a billable ICD-10-CM diagnosis code for injury of optic chiasm, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 963 through 965. Coders also document this condition as injury of optic chiasm. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, initial encounter.

Code Identity

ICD-10-CM Code
S04.02XA
Billable Status
Yes — Valid for Submission
Code Describes
Injury of optic chiasm, initial encounter
Short Description
Injury of optic chiasm, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S04.02
Injury of optic chiasm

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS00-S09Injuries to the head
CategoryS04Injury of cranial nerve
This CodeS04.02XAInjury of optic chiasm, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Injury of optic chiasm

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of cranial nerve (S04). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ025
Injury to nerves, muscles and tendons, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Optic Nerve Disorders

The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye (your retina) to your brain. Damage to an optic nerve can cause vision loss. The type of vision loss and how severe it is depends on where the damage occurs. It may affect one or both eyes.

Read the full article at MedlinePlus

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

Convert S04.02XA to ICD-9-CMHistory

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

ICD-9-CM
950.1 Injury to optic chiasm
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 S04.02XAOverview

Is S04.02XA (Injury of optic chiasm) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report injury of optic chiasm, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in S04.02XA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for injury of optic chiasm, such as an emergency visit or first evaluation.

What MS-DRG does S04.02XA group to?

When injury of optic chiasm, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 963, 964, 965, with relative weights from 0.9405 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S04.02XA?

Under the General Equivalence Mappings, injury of optic chiasm, initial encounter converts to ICD-9-CM 950.1 (injury to optic chiasm). 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.