ICD-10 Code H33.121 – Parasitic cyst of retina, right eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H33.121 – Parasitic cyst of retina, right eye
What it is
This code identifies a parasitic cyst located in the retina of the right eye. Use it when documentation specifically states a retinal cyst caused by a parasite.
Clinical signs
Clinical features vary; refer to documentation. Findings may include a retinal cyst seen on eye examination or imaging, with visual symptoms if the lesion affects central vision.
When to use this code
Use H33.121 when the provider documents a parasitic cyst of the retina in the right eye. It is appropriate for ophthalmology notes, consults, or imaging reports that clearly identify the right-eye location and parasitic cause.
If the record only mentions a retinal cyst without parasite involvement, check documentation before coding. You should also confirm laterality, because this code is specific to the right eye.
Do not use for
Do not use this code for nonparasitic retinal cysts or for eye conditions without retinal involvement. If the parasite site or laterality is unclear, check documentation.
Coding tip
Always verify both the parasitic etiology and right-eye laterality in the chart before assigning H33.121.