H50.641 ICD-10-CM Code: Lateral rectus muscle entrapment, right eye

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for H50.641 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on H50.641 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for H50.641

MedCoder structured workflow — derived from this code’s own official record

Before you code H50.641

1. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: right). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

   ReviewH50.642 · left, H50.649 · unspecified

   Guide: Laterality coding →

Choose the right path

1. Is the side documented?
   Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
   No → Use the unspecified-side code only when the record states no side; a query is the alternative.

   ReviewH50.642 · left, H50.649 · unspecified

Consider H50.641. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Laterality

Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).

Official instructions as workflow

• Excludes2 — not part of H50.641(1 note)

  Coding workflow: The conditions named in this note are not included in H50.641. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareH55

  See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse H50.641 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of H50.641 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• H50.649— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Lateral rectus muscle entrapment, unspecified eye” takes H50.649; specificity in the record moves it back here.

  Full comparison: H50.641 vs H50.649 →

• H50.642— Laterality relationship (Review)

  Same condition; these differ only in which side is documented.

  The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

  What moves you there: A documented left side moves the case to H50.642.

  Full comparison: H50.641 vs H50.642 →

• H55— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of nystagmus and other irregular eye movements adds H55; it is not part of this code and both may be reported when both are documented.

  Full comparison: H50.641 vs H55 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name H50.641 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes2 note: H53.03 — Strabismic amblyopia (via H50.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 124 (MDC 02), DRG 125 (MDC 02).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):EYE007 — Strabismus (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same condition, opposite side

Same category and title, differing only in which side of the body is affected.

H50.642 — Lateral rectus muscle entrapment, left eye (left)Compare H50.641 vs H50.642 →, H50.649 — Lateral rectus muscle entrapment, unspecified eye (unspecified)Compare H50.641 vs H50.649 →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Strabismus).

H50.55 — Alternating heterophoria, H50.60 — Mechanical strabismus, unspecified, H50.611 — Brown's sheath syndrome, right eye, H50.612 — Brown's sheath syndrome, left eye, H50.621 — Inferior oblique muscle entrapment, right eye, H50.622 — Inferior oblique muscle entrapment, left eye, H50.629 — Inferior oblique muscle entrapment, unspecified eye, H50.631 — Inferior rectus muscle entrapment, right eye, H50.632 — Inferior rectus muscle entrapment, left eye, H50.639 — Inferior rectus muscle entrapment, unspecified eye, H50.642 — Lateral rectus muscle entrapment, left eye, H50.649 — Lateral rectus muscle entrapment, unspecified eye, H50.651 — Medial rectus muscle entrapment, right eye, H50.652 — Medial rectus muscle entrapment, left eye, H50.659 — Medial rectus muscle entrapment, unspecified eye, H50.661 — Superior oblique muscle entrapment, right eye, H50.662 — Superior oblique muscle entrapment, left eye, H50.669 — Superior oblique muscle entrapment, unspecified eye, H50.671 — Superior rectus muscle entrapment, right eye, H50.672 — Superior rectus muscle entrapment, left eye, +83 more

Contextual Map

Every relationship of H50.641 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run H50.641 with this related code in Claim Check

Hierarchy

• H00-H59 — Chapter 7: Diseases of the Eye and Adnexa (H00-H59) (H00-H59)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H49-H52 — Disorders of ocular muscles, binocular movement, accommodation and refraction[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes2 notes

• H53.03 — Strabismic amblyopia[Excludes2](via H50.-): “strabismus (H50.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• EYE007 — Strabismus[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 124 — OTHER DISORDERS OF THE EYE WITH MCC OR THROMBOLYTIC AGENT[MS-DRG]: “OTHER DISORDERS OF THE EYE WITH MCC OR THROMBOLYTIC AGENT (MDC 02)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 125 — OTHER DISORDERS OF THE EYE WITHOUT MCC[MS-DRG]: “OTHER DISORDERS OF THE EYE WITHOUT MCC (MDC 02)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 02 — Diseases and Disorders of the Eye[MDC crossing]: “Diseases and Disorders of the Eye — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1,200 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Nearest codes (40)

• H50 — Other strabismus[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.50 — Unspecified heterophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.51 — Esophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.52 — Exophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.53 — Vertical heterophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.54 — Cyclophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.55 — Alternating heterophoria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H50.6 — Mechanical strabismus[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

Change history

• FY2024 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2024

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to H50.641 in its code family, with their registry titles.

• H50.63 — Inferior rectus muscle entrapment
• H50.631 — Inferior rectus muscle entrapment, right eye
• H50.632 — Inferior rectus muscle entrapment, left eye
• H50.639 — Inferior rectus muscle entrapment, unspecified eye
• H50.64 — Lateral rectus muscle entrapment
• H50.642 — Lateral rectus muscle entrapment, left eye
• H50.649 — Lateral rectus muscle entrapment, unspecified eye
• H50.65 — Medial rectus muscle entrapment
• H50.651 — Medial rectus muscle entrapment, right eye
• H50.652 — Medial rectus muscle entrapment, left eye

View all codes in the H50 family