2026 ICD-10-CM Diagnosis Code H42Glaucoma in diseases classified elsewhere
ICD-10-CM Codes›H00–H59›H40-H42›H42
- Billable — Valid for Submission
- Chronic Condition
H42 is a billable ICD-10-CM diagnosis code for glaucoma in diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 124 through 125. The code is a manifestation code that cannot be reported as the principal diagnosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Glaucoma.
H42 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 244 for payment year 2026.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for H42.
Medicare Risk Adjustment (HCC)Billing
H42 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bilateral glaucoma due to systemic syndrome
- Bilateral open angle glaucoma due to vascular disorder
- Bilateral secondary angle closure glaucoma
- Glaucoma and sleep apnea syndrome
- Glaucoma due to combination of mechanisms
- Glaucoma due to congenital anomaly of eye
- Glaucoma due to diabetes mellitus
- Glaucoma due to diabetes mellitus type 1
- Glaucoma due to Lowe syndrome
- Glaucoma due to systemic syndrome
- Glaucoma in endocrine, nutritional and metabolic diseases
- Glaucoma of left eye due to systemic syndrome
- Glaucoma of right eye due to systemic syndrome
- Neovascular angle closure glaucoma
- Neovascular glaucoma due to diabetes mellitus
- Neovascular glaucoma due to diabetes mellitus type 1
- Neovascular glaucoma due to diabetes mellitus type 2
- Open angle glaucoma due to vascular disorder
- Open angle glaucoma of left eye due to vascular disorder
- Open angle glaucoma of right eye due to vascular disorder
- Phacomorphic secondary acute angle closure
- Secondary acute angle closure
- Secondary acute angle closure due to neovascularization
- Secondary acute angle closure due to uveitis
- Secondary angle closure
- Secondary angle closure due to neovascularization
- Secondary angle closure due to uveitis
- Secondary angle closure glaucoma of left eye
- Secondary angle-closure glaucoma
- Secondary angle-closure glaucoma of right eye
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Code First
- underlying condition, such as:
- amyloidosis E85
- aniridia Q13.1
- glaucoma in diabetes mellitus E08.39 E09.39 E10.39 E11.39 E13.39
- Lowe's syndrome E72.03
- Rieger anomaly Q13.81
- specified metabolic disorder E70 E88
Type 1 Excludes
- glaucoma in onchocerciasis B73.02
- glaucoma in syphilis A52.71
- glaucoma in tuberculous A18.59
- neovascular secondary angle closure glaucoma H40.84
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Glaucoma
Glaucoma is a group of diseases that can damage the optic nerve of one, or both, of your eyes. This can result in vision loss. There are different types of glaucoma, but the most common type is open-angle glaucoma. Other less common types include angle-closure glaucoma, and congenital glaucoma.
The full article covers:
- What is glaucoma?
- What causes glaucoma?
- What are the symptoms of glaucoma?
- How is glaucoma diagnosed?
- What are the treatments for glaucoma?
- Can glaucoma be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert H42 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About H42Overview
What is the ICD-10 code for glaucoma in diseases classified elsewhere?
The ICD-10-CM code for glaucoma in diseases classified elsewhere is H42. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is H42 (Glaucoma in diseases classified elsewhere) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report glaucoma in diseases classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does H42 group to?
On inpatient claims, glaucoma in diseases classified elsewhere maps to MS-DRG 124, 125, with relative weights from 0.7678 to 1.3231 depending on complications. Higher weights mean higher Medicare reimbursement.
Can H42 be a principal diagnosis?
No. This is a manifestation code: glaucoma in diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
What is the ICD-9 equivalent of H42?
Under the General Equivalence Mappings, glaucoma in diseases classified elsewhere converts to ICD-9-CM 365.44 (glaucoma w systemic synd). The mapping is approximate, so confirm the match fits the documentation.
Does H42 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage: H42 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 244 (Other Non-Acute Glaucoma).
