H21.331Parasitic cyst of iris, ciliary body or anterior chamber, right eye

H21.331 is the ICD-10-CM diagnosis code for parasitic cyst of iris, ciliary body or anterior chamber, right eye. It belongs to category H21 (other disorders of iris and ciliary body), block H15-H22 (disorders of sclera, cornea, iris and ciliary body) and chapter 7 (diseases of the eye and adnexa). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within H21.33 (parasitic cyst of iris, ciliary body or anterior chamber), H21.331 is specifically for parasitic cyst of iris, ciliary body or anterior chamber, right eye. Related codes cover left eye (H21.332), bilateral (H21.333) and unspecified eye (H21.339).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 121 (Acute Major Eye Infections with CC/MCC, relative weight 1.2255) and DRG 122 (Acute Major Eye Infections without CC/MCC, relative weight 0.7406), in MDC 02 (Diseases and Disorders of the Eye), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 360.13 (parasitic endophthalmitis NOS).