ICD-10 Code H21.321 – Implantation cysts of iris, ciliary body or anterior chamber, right eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H21.321 – Implantation cysts of iris, ciliary body or anterior chamber, right eye
What it is
This code identifies an implantation cyst involving the iris, ciliary body, or anterior chamber of the right eye. It indicates a localized cystic lesion, usually documented by the eye provider.
Clinical signs
Clinical features vary; refer to documentation. Findings may include a visible cystic lesion on eye examination or imaging, with symptoms depending on size and location.
When to use this code
Use H21.321 when the provider documents an implantation cyst in the right eye and specifies the iris, ciliary body, or anterior chamber. Code it from ophthalmology notes, operative reports, or follow-up assessments that clearly identify laterality and site.
If the record only says “ocular cyst” or does not specify the right eye, you need more documentation before assigning this code.
Do not use for
Do not use this code for cysts in the left eye or unspecified eye. Do not assign it when the lesion is another type of anterior segment mass or when documentation does not confirm an implantation cyst.
Coding tip
Verify both laterality and anatomic site in the note before coding; H21.321 is specific to the right eye.