2027 ICD-10-CM Diagnosis Code H20.00Unspecified acute and subacute iridocyclitis

ICD-10-CM Codes›H00–H59›H15-H22›H20

ICD-10-CM H20.00
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H20.00 is a billable ICD-10-CM diagnosis code for unspecified acute and subacute iridocyclitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 124 through 125. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 39 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Uveitis and ocular inflammation.

Code Identity

ICD-10-CM Code
H20.00
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified acute and subacute iridocyclitis
Short Description
Unspecified acute and subacute iridocyclitis
Same as the full description in the CMS dataset.
Parent Code
H20.0
Acute and subacute iridocyclitis

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH15-H22Disorders of sclera, cornea, iris and ciliary body
CategoryH20Iridocyclitis
This CodeH20.00Unspecified acute and subacute iridocyclitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute anterior uveitis
  • Acute anterior uveitis of bilateral eyes
  • Acute anterior uveitis of left eye
  • Acute anterior uveitis of right eye
  • Acute cyclitis
  • Acute iridocyclitis
  • Acute iritis
  • Acute iritis of left eye
  • Acute iritis of right eye
  • Anterior chamber - abnormal contents
  • Bilateral acute iritis
  • Bilateral subacute iridocyclitis
  • Fibrin in anterior chamber
  • Human leukocyte antigen B27 detected
  • Human leukocyte antigen B27 positive acute anterior uveitis
  • Idiopathic acute anterior uveitis
  • Idiopathic anterior uveitis
  • Idiopathic subacute anterior uveitis
  • Iridocyclitis of bilateral eyes
  • Iritis with psoriatic arthritis
  • Lepromatous anterior uveitis
  • Lepromatous leprosy
  • Psoriatic arthritis
  • Subacute anterior uveitis
  • Subacute cyclitis
  • Subacute iridocyclitis
  • Subacute iridocyclitis of left eye
  • Subacute iridocyclitis of right eye
  • Subacute iritis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H20.00: its own notes plus those printed at H20.0 and Chapter 7. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From H20.0 Acute and subacute iridocyclitis applies to 21 codes
  • iridocyclitis, iritis, uveitis (due to) (in) diabetes mellitus (E08-E13 with .39)
  • iridocyclitis, iritis, uveitis (due to) (in) diphtheria (A36.89)
  • iridocyclitis, iritis, uveitis (due to) (in) gonococcal (A54.32)
  • iridocyclitis, iritis, uveitis (due to) (in) herpes (simplex) (B00.51)
  • iridocyclitis, iritis, uveitis (due to) (in) herpes zoster (B02.32)
  • iridocyclitis, iritis, uveitis (due to) (in) late congenital syphilis (A50.39)
  • iridocyclitis, iritis, uveitis (due to) (in) late syphilis (A52.71)
  • iridocyclitis, iritis, uveitis (due to) (in) sarcoidosis (D86.83)
  • iridocyclitis, iritis, uveitis (due to) (in) syphilis (A51.43)
  • iridocyclitis, iritis, uveitis (due to) (in) toxoplasmosis (B58.09)
  • iridocyclitis, iritis, uveitis (due to) (in) tuberculosis (A18.54)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury (trauma) of eye and orbit (S05.-)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)

Notes

General instructions on how these codes are used.

From Chapter 7 (H00-H59) Diseases of the eye and adnexa applies to 2,677 codes
  • Use an external cause code following the code for the eye condition, if applicable, to identify the cause of the eye condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Clinical ClassificationClinical

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

CCSR EYE004
Uveitis and ocular inflammation
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Iridocyclitis

    acute or chronic inflammation of the iris and ciliary body characterized by exudates into the anterior chamber, discoloration of the iris, and constricted, sluggish pupil. symptoms include radiating pain, photophobia, lacrimation, and interference with vision.

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 H20.00 to ICD-9-CMHistory

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

ICD-9-CM
364.00 Acute iridocyclitis NOS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About H20.00Overview

What is the ICD-10 code for unspecified acute and subacute iridocyclitis?

The ICD-10-CM code for unspecified acute and subacute iridocyclitis is H20.00 (sometimes written as H2000). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is H20.00 (Acute and subacute iridocyclitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified acute and subacute iridocyclitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does H20.00 group to?

When unspecified acute and subacute iridocyclitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 125, 124, with relative weights from 0.7699 to 1.2470 depending on complications. Higher weights mean higher Medicare reimbursement.

Is H20.00 a CC or MCC?

CMS lists H20.00 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 39 closely related codes in its exclusion list.

Can H20.00 be reported with A36.89?

Not as a rule. The Excludes1 note at H20.0, which applies to H20.00, lists "iridocyclitis, iritis, uveitis (due to) (in) diphtheria (A36.89)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).