ICD-10 Code H42 – Glaucoma in diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H42 – Glaucoma in diseases classified elsewhere
What it is
This code identifies glaucoma that occurs as a complication of another underlying disease. Use it when the glaucoma is documented as secondary to a different condition.
Clinical signs
Findings may include optic nerve damage, visual field loss, and elevated intraocular pressure, but clinical features vary; refer to documentation. The record should link the glaucoma to the causative disease.
When to use this code
Use H42 when the provider states that glaucoma is due to another disease, such as an ocular or systemic condition. Code the underlying disorder as well, when documented. If the cause is unclear, check documentation before assigning this code.
Do not use for
Do not use this code for primary glaucoma or for glaucoma without a documented underlying cause. If the chart only says “glaucoma” or the relationship is not specified, choose a more specific code only if supported by the record.
Coding tip
Always code the underlying disease first when it is the reason the glaucoma is classified elsewhere.