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H18.23 ICD-10-CM Code: Secondary corneal edema

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Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

The tabular list publishes no instructional note for this code itself.

Where it sits Source: CMS/NCHS

Under:Chapter 7: Diseases of the Eye and AdnexaH15-H22 Disorders of sclera, cornea, iris and ciliary bodyH18 Other disorders of corneaH18.2 Other and unspecified corneal edema

Codes under H18.23 (4)

  • H18.231Secondary corneal edema, right eyeBillable
  • H18.232Secondary corneal edema, left eyeBillable
  • H18.233Secondary corneal edema, bilateralBillable
  • H18.239Secondary corneal edema, unspecified eyeBillable

CompareCheck ClaimView Related Codes

Coder workflow for H18.23

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

Before you code H18.23

  1. H18.23 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).

    ReviewH18.231, H18.232, H18.233, H18.239

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

Choose the right path

  1. Does the documentation support one of the more specific codes beneath H18.23?
    Yes → Select that code and continue the checks below on its own page.
    No → H18.23 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewH18.231, H18.232, H18.233, H18.239

Report the code beneath H18.23 that the documentation supports, not H18.23 itself. Then confirm that code is valid for the date of service on its own page.

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).

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 H18.23 with…

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

The codes most likely to be picked instead of H18.23 — 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.

  • H18.20— 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 “Unspecified corneal edema” takes H18.20; specificity in the record moves it back here.

    Full comparison: H18.23 vs H18.20 →

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.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Secondary corneal edema is a non-billable ICD-10-CM category code (H18.23). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

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

Related Codes

Same Index main term, other category

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

G95.19 — Other vascular myelopathies (spinal), H02.841 — Edema of right upper eyelid (eyelid NEC, right, upper), H02.842 — Edema of right lower eyelid (eyelid NEC, right, lower), H02.843 — Edema of right eye, unspecified eyelid (eyelid NEC, right), H02.844 — Edema of left upper eyelid (eyelid NEC, left, upper), H02.845 — Edema of left lower eyelid (eyelid NEC, left, lower), H02.846 — Edema of left eye, unspecified eyelid (eyelid NEC, left), H02.849 — Edema of unspecified eye, unspecified eyelid (eyelid NEC), H05.22 — Edema of orbit (orbit), H11.42 — Conjunctival edema (conjunctiva), H21.89 — Other specified disorders of iris and ciliary body (iris), H35.81 — Retinal edema (macula), I50.1 — Left ventricular failure, unspecified (lung, meaning failure, left ventricle), I73.9 — Peripheral vascular disease, unspecified (angiospastic), I87.1 — Compression of vein (legs, due to venous obstruction), I89.0 — Lymphedema, not elsewhere classified (lymphatic), I97.2 — Postmastectomy lymphedema syndrome (lymphatic, due to mastectomy), J38.4 — Edema of larynx (glottis, glottic, glottidis), J39.2 — Other diseases of pharynx (pharynx), J68.1 — Pulmonary edema due to chemicals, gases, fumes and vapors (lung, chemical), +32 more

Contextual Map

Every relationship of H18.23 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.

Hierarchy

Nearest codes (40)

Change history

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

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can H18.23 be billed directly?

No. H18.23 (Secondary corneal edema) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "H18.23 — Secondary corneal edema." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/h18.23-secondary-corneal-edema

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Secondary corneal edema

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to H18.23 in its code family, with their registry titles.

View all codes in the H18 family