H40.10 ICD-10-CM Code: Unspecified open-angle glaucoma

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for H40.10 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 H40.10 itself; “inherited from” names the category or block whose note applies here.

7th Character Guide

"One of the following 7th characters is to be assigned to code H40.10 to designate the stage of glaucoma"

• 0 — stage unspecified
• 1 — mild stage
• 2 — moderate stage
• 3 — severe stage
• 4 — indeterminate stage

Variant codes in this family

H40.10X0, H40.10X1, H40.10X2, H40.10X3, H40.10X4

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for H40.10

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

Before you code H40.10

1. H40.10 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

   ReviewH40.10X0, H40.10X1, H40.10X2, H40.10X3, H40.10X4

   See the relationships section · Guide: How to choose an ICD-10-CM code →

2. Unspecified does not mean incorrect. When the record gives no greater specificity, H40.10 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by open versus closed. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   ReviewH40.11

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

3. A 7th character is required in this family. Confirm the documentation supports the character assigned — its meaning in this family is defined in the official instruction. H40.10 is not valid without one. The official 7th-character definitions for this family are quoted in the guide.

   See the 7th Character Guide

4. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with H40.10. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support one of the more specific codes beneath H40.10?
   Yes → Select that code and continue the checks below on its own page.
   No → H40.10 cannot be reported as written; query for the specificity its subcategory needs.

   ReviewH40.10X0, H40.10X1, H40.10X2, H40.10X3, H40.10X4

2. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — H40.10 is appropriate when the documentation goes no further.

   ReviewH40.11

3. Does the documentation support a condition named in H40.10’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewH44.51, Q15.0, P15.3

4. Does the documentation support one of this family’s 7th-character values?
   Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
   No → The code is invalid without its 7th character — query for the missing element.

Consider H40.10. 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).

7th-character basis

The documented element this family’s 7th character records (see the official definitions in the 7th Character Guide).

Open or closed; displaced or nondisplaced

Defaults apply when the record is silent: closed, and displaced (Guidelines I.C.19.c).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes1 — check before selecting H40.10(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with H40.10: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareH44.51, Q15.0, P15.3

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

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.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Don’t confuse H40.10 with…

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

The codes most likely to be picked instead of H40.10 — 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.

• H44.51— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of absolute glaucoma moves the case to H44.51; the two are not reported together unless documented as unrelated.

  Full comparison: H40.10 vs H44.51 →

• Q15.0— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of congenital glaucoma moves the case to Q15.0; the two are not reported together unless documented as unrelated.

  Full comparison: H40.10 vs Q15.0 →

• P15.3— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of traumatic glaucoma due to birth injury moves the case to P15.3; the two are not reported together unless documented as unrelated.

  Full comparison: H40.10 vs P15.3 →

• H40.10X0— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a stage unspecified moves the case to H40.10X0.

  Full comparison: H40.10 vs H40.10X0 →

• H40.10X1— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a mild stage moves the case to H40.10X1.

  Full comparison: H40.10 vs H40.10X1 →

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

• Not billable as written — a more specific code is required: H40.10X0, H40.10X1, H40.10X2, H40.10X3, H40.10X4.
• Requires a 7th character. "One of the following 7th characters is to be assigned to code H40.10 to designate the stage of glaucoma" Options: H40.10X0, H40.10X1, H40.10X2, H40.10X3, H40.10X4

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 H40.10 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: H25 — Age-related cataract (via H40.1.-).

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

Referenced by 1 Code First instruction: H26.23 — Glaucomatous flecks (subcapsular) (via H40.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 5 Use Additional Code instructions: E08.39 — Diabetes mellitus due to underlying condition with other diabetic ophthalmic complication (via H40.-), E09.39 — Drug or chemical induced diabetes mellitus with other diabetic ophthalmic complication (via H40.-), E10.39 — Type 1 diabetes mellitus with other diabetic ophthalmic complication (via H40.-), E11.39 — Type 2 diabetes mellitus with other diabetic ophthalmic complication (via H40.-), E13.39 — Other specified diabetes mellitus with other diabetic ophthalmic complication (via H40.-).

These codes instruct coders to additionally report this code when it applies.

Related Codes

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Glaucoma”; these codes share that main term but sit in a different category of the Tabular List.

A18.59 — Other tuberculosis of eye (tuberculous), A52.71 — Late syphilitic oculopathy (syphilitic), B73.02 — Onchocerciasis with glaucoma (in, onchocerciasis), E34.9 — Endocrine disorder, unspecified (in, endocrine disease NOS), E72.03 — Lowe's syndrome (in, Lowe's syndrome), E85.4 — Organ-limited amyloidosis (in, amyloidosis), E88.9 — Metabolic disorder, unspecified (in, metabolic disease NOS), H44.51 — Absolute glaucoma (absolute), P15.3 — Birth injury to eye (traumatic, newborn), Q13.1 — Absence of iris (in, aniridia), Q13.81 — Rieger anomaly (in, Rieger anomaly), Q15.0 — Congenital glaucoma (newborn)

Contextual Map

Every relationship of H40.10 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 H40.10 with these 7 related codes 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
• H40-H42 — Glaucoma[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes2 notes

• H25 — Age-related cataract[Excludes2](via H40.1.-): “capsular glaucoma with pseudoexfoliation of lens (H40.1-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• H26.23 — Glaucomatous flecks (subcapsular)[Code First](via H40.-): “underlying glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Use Additional Code instructions

• E08.39 — Diabetes mellitus due to underlying condition with other diabetic ophthalmic complication[Use Additional Code](via H40.-): “diabetic glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• E09.39 — Drug or chemical induced diabetes mellitus with other diabetic ophthalmic complication[Use Additional Code](via H40.-): “diabetic glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• E10.39 — Type 1 diabetes mellitus with other diabetic ophthalmic complication[Use Additional Code](via H40.-): “diabetic glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• E11.39 — Type 2 diabetes mellitus with other diabetic ophthalmic complication[Use Additional Code](via H40.-): “diabetic glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• E13.39 — Other specified diabetes mellitus with other diabetic ophthalmic complication[Use Additional Code](via H40.-): “diabetic glaucoma (H40-H42)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Nearest codes (40)

• H40 — Glaucoma[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.031 — Anatomical narrow angle, right eye[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.032 — Anatomical narrow angle, left eye[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.033 — Anatomical narrow angle, bilateral[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.039 — Anatomical narrow angle, unspecified eye[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.04 — Steroid responder[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.041 — Steroid responder, right eye[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• H40.042 — Steroid responder, left eye[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

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

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section 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

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 H40.10 in its code family, with their registry titles.

• H40.061 — Primary angle closure without glaucoma damage, right eye
• H40.062 — Primary angle closure without glaucoma damage, left eye
• H40.063 — Primary angle closure without glaucoma damage, bilateral
• H40.069 — Primary angle closure without glaucoma damage, unspecified eye
• H40.1 — Open-angle glaucoma
• H40.10X0 — Unspecified open-angle glaucoma, stage unspecified
• H40.10X1 — Unspecified open-angle glaucoma, mild stage
• H40.10X2 — Unspecified open-angle glaucoma, moderate stage
• H40.10X3 — Unspecified open-angle glaucoma, severe stage
• H40.10X4 — Unspecified open-angle glaucoma, indeterminate stage

View all codes in the H40 family