H51.21
BillableInternuclear ophthalmoplegia, right eye
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is H51.21 an HCC code?
No. H51.21 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
H51.21 is the ICD-10-CM diagnosis code for internuclear ophthalmoplegia, right eye. A neurological condition affecting the right eye where the eye cannot move inward properly due to a brainstem lesion, though outward movement is preserved. H51.21 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of ocular muscles, binocular movement, accommodation and refraction (h49-h52).
H51.21 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This is a specific brainstem syndrome; document the underlying cause if identified.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for H51.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a specific brainstem syndrome; document the underlying cause if identified
- •Verify laterality is correctly specified as right eye only