ICD-10 Code H40.03 – Anatomical narrow angle (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H40.03 – Anatomical narrow angle
What it is
H40.03 identifies an anatomically narrow anterior chamber angle in the eye. Use it when documentation shows a narrow angle configuration, with or without symptoms, and without a confirmed glaucoma diagnosis.
Clinical signs
Findings may include a shallow anterior chamber or gonioscopic evidence of a narrow angle. Clinical features vary; refer to documentation for whether the angle is occludable, intermittent, or associated with elevated eye pressure.
When to use this code
Use this code when the record documents narrow angle anatomy during an eye exam or specialist evaluation. It also fits preglaucoma or surveillance visits when the provider notes narrow angles but does not diagnose primary angle-closure glaucoma. If the note is unclear, check documentation.
Do not use for
Do not use H40.03 for confirmed glaucoma, angle-closure disease, or other specified eye disorders unless the provider documents narrow angle anatomy separately. Do not assume the code from symptoms alone.
Coding tip
Code only when the provider documents the anatomical narrow angle finding; if the angle status is not explicit, check documentation.