2026 ICD-10-CM Diagnosis Code A18.51Tuberculous episcleritis

ICD-10-CM Codes›A00–B99›A15-A19›A18

ICD-10-CM A18.51
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A18.51 is a billable ICD-10-CM diagnosis code for tuberculous episcleritis. 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, 974 through 976. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease and Tuberculosis.

Code Identity

ICD-10-CM Code
A18.51
Billable Status
Yes — Valid for Submission
Code Describes
Tuberculous episcleritis
Short Description
Tuberculous episcleritis
Same as the full description in the CMS dataset.
Parent Code
A18.5
Tuberculosis of eye

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA15-A19Tuberculosis
CategoryA18Tuberculosis of other organs
This CodeA18.51Tuberculous episcleritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral episcleritis of eyes
  • Bilateral episcleritis of eyes caused by Mycobacterium tuberculosis
  • Bilateral scleritis of eyes
  • Episcleritis caused by Mycobacterium tuberculosis
  • Episcleritis of left eye
  • Episcleritis of left eye caused by Mycobacterium tuberculosis
  • Episcleritis of right eye
  • Episcleritis of right eye caused by Mycobacterium tuberculosis
  • Tuberculous episcleritis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Episcleritis(suppurative)
      • in (due to)
        • tuberculosis
    • Episcleritis(suppurative)
      • tuberculous
    • Scleritis
      • tuberculous (nodular)
    • Tuberculosis, tubercular, tuberculous(calcification) (calcified) (caseous) (chromogenic acid-fast bacilli) (degeneration) (fibrocaseous) (fistula) (interstitial) (isolated circumscribed lesions) (necrosis) (parenchymatous) (ulcerative)
      • episcleritis
    • Tuberculosis, tubercular, tuberculous(calcification) (calcified) (caseous) (chromogenic acid-fast bacilli) (degeneration) (fibrocaseous) (fistula) (interstitial) (isolated circumscribed lesions) (necrosis) (parenchymatous) (ulcerative)
      • sclera

Clinical ClassificationClinical

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

CCSR EYE001
Cornea and external disease
Default principal diagnosis: inpatient No · outpatient No
CCSR INF001
Tuberculosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Eye Infections

Your eyes can get infections from bacteria, fungi, or viruses. Eye infections can occur in different parts of the eye and can affect just one eye or both. Two common eye infections are:

Read the full article at MedlinePlus

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

Convert A18.51 to ICD-9-CMHistory

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

ICD-9-CM
017.30 TB of eye-unspec
Approximate The match is approximate rather than exact.
ICD-9-CM
017.30 TB of eye-unspec
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
379.09 Scleritis NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 A18.51Overview

Is A18.51 (Tuberculosis of eye) a billable code?

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

What MS-DRG does A18.51 group to?

When tuberculous episcleritis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 124, 125, 974, 975, 976, with relative weights from 0.7678 to 2.8860 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A18.51?

Under the General Equivalence Mappings, tuberculous episcleritis converts to ICD-9-CM 017.30 (TB of eye-unspec), 017.30 (TB of eye-unspec), and 379.09 (scleritis NEC). 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.