ICD-10 Code H21.333 – Parasitic cyst of iris, ciliary body or anterior chamber, bilateral (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H21.333 – Parasitic cyst of iris, ciliary body or anterior chamber, bilateral
What it is
This code identifies a parasitic cyst affecting both eyes’ anterior segment structures: the iris, ciliary body, or anterior chamber. Use it when documentation specifies bilateral involvement and a parasitic cause.
Clinical signs
Findings may include visible cystic lesions in the anterior chamber or on the iris, with possible inflammation, photophobia, or blurred vision. Clinical features vary; refer to documentation.
When to use this code
Use H21.333 when the provider documents a parasitic cyst in both eyes involving the iris, ciliary body, or anterior chamber. The record should clearly support bilateral disease and a parasitic etiology. If laterality or cause is not stated, check documentation.
Do not use for
Do not use this code for nonparasitic cysts, unilateral disease, or cysts in other ocular locations. If the chart does not confirm a parasitic origin, check documentation.
Coding tip
Confirm both laterality and the exact anatomic site before assigning H21.333.