ICD-10 Code H21.339 – Parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H21.339 – Parasitic cyst of iris, ciliary body or anterior chamber, unspecified eye
What it is
This code identifies a parasitic cyst involving the iris, ciliary body, or anterior chamber of the eye, when the affected eye is not specified. Use it for a documented parasitic lesion in one of these anterior segment structures.
Clinical signs
Findings may include a visible cystic lesion in the anterior chamber or on the iris, with eye irritation, redness, or blurred vision. Clinical features vary; refer to documentation.
When to use this code
Use H21.339 when the clinician documents a parasitic cyst in the iris, ciliary body, or anterior chamber and does not name the right or left eye. It is appropriate when the record supports a parasitic cause but laterality is missing. Check documentation if the note is vague or only mentions an intraocular cyst.
Do not use for
Do not use this code for nonparasitic cysts, unspecified ocular masses, or lesions in other eye structures. If the diagnosis is another anterior segment disorder, code that condition instead.
Coding tip
Always verify both the parasitic etiology and the eye laterality before assigning H21.339.