2026 ICD-10-CM Diagnosis Code S04.012AInjury of optic nerve, left eye, initial encounter
S04.012A is a billable ICD-10-CM diagnosis code for injury of optic nerve, left eye, 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 124 through 125, 963 through 965. Coders also document this condition as bilateral injury of optic nerve. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bilateral injury of optic nerve
- Injury of both visual cortices
- Injury of left visual cortex
- Injury of right visual cortex
- Traumatic injury of left optic nerve
- Traumatic injury of left visual pathway
- Traumatic optic nerve injury
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.
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 S04.012A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S04.012AOverview
Is S04.012A (Injury of optic nerve, left eye) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report injury of optic nerve, left eye, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S04.012A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for injury of optic nerve, such as an emergency visit or first evaluation.
What MS-DRG does S04.012A group to?
When injury of optic nerve, left eye, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 124, 125, 963, 964, 965, with relative weights from 0.7678 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S04.012A?
Under the General Equivalence Mappings, injury of optic nerve, left eye, initial encounter converts to ICD-9-CM 950.0 (optic nerve injury). 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.
