2027 ICD-10-CM Diagnosis Code H21.503Unspecified adhesions of iris, bilateral

ICD-10-CM Codes›H00–H59›H15-H22›H21

ICD-10-CM H21.503
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

H21.503 is a billable ICD-10-CM diagnosis code for unspecified adhesions of iris, bilateral. 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. Coders also document this condition as bilateral synechia of irises. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified eye disorders.

Code Identity

ICD-10-CM Code
H21.503
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified adhesions of iris, bilateral
Short Description
Unspecified adhesions of iris, bilateral
Same as the full description in the CMS dataset.
Parent Code
H21.50
Unspecified adhesions of iris

Code Classification

ChapterH00–H59Diseases of the eye and adnexa
SectionH15-H22Disorders of sclera, cornea, iris and ciliary body
CategoryH21Other disorders of iris and ciliary body
This CodeH21.503Unspecified adhesions of iris, bilateral

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral synechia of irises

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to H21.503: its own notes plus those printed at H21.5, H21, 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 H21.5 Other and unspecified adhesions and disruptions of iris and ciliary body applies to 28 codes

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 H21 Other disorders of iris and ciliary body applies to 97 codes
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 EYE012
Other specified eye disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

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Convert H21.503 to ICD-9-CMHistory

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

ICD-9-CM
364.70 Adhesions of iris NOS
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About H21.503Overview

What is the ICD-10 code for unspecified adhesions of iris, bilateral?

The ICD-10-CM code for unspecified adhesions of iris, bilateral is H21.503 (sometimes written as H21503). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is H21.503 (Unspecified adhesions of iris) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified adhesions of iris, bilateral on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does H21.503 group to?

When unspecified adhesions of iris, bilateral 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.

Can H21.503 be reported with Q13.2?

Not as a rule. The Excludes1 note at H21.5, which applies to H21.503, lists "corectopia (Q13.2)". 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).

What is the ICD-9 equivalent of H21.503?

Under the General Equivalence Mappings, unspecified adhesions of iris, bilateral converts to ICD-9-CM 364.70 (adhesions of iris NOS). The mapping is approximate, so confirm the match fits the documentation.