ICD-10 Code H21.303 – Idiopathic cysts of iris, ciliary body or anterior chamber, bilateral (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H21.303 – Idiopathic cysts of iris, ciliary body or anterior chamber, bilateral
What it is
This code identifies bilateral idiopathic cysts involving the iris, ciliary body, or anterior chamber. “Idiopathic” means the cause is not documented or not known.
Clinical signs
Findings may include visible cystic lesions on eye examination, sometimes noted incidentally. Clinical features vary; refer to documentation for laterality, location, and any associated symptoms.
When to use this code
Use H21.303 when the provider documents idiopathic cysts in both eyes and specifies the iris, ciliary body, or anterior chamber. It fits cases where no underlying cause is identified in the record. If the note names another cause or different laterality, code that documented condition instead.
Do not use for
Do not use this code for cysts with a documented cause, such as trauma or surgery-related changes. Do not use it when the lesion is unilateral or when the chart does not confirm bilateral involvement.
Coding tip
Check the ophthalmology note for exact site, laterality, and whether the cyst is idiopathic before assigning H21.303.