ICD-10 Code H51.21 – Internuclear ophthalmoplegia, right eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H51.21 – Internuclear ophthalmoplegia, right eye
What it is
Internuclear ophthalmoplegia is a disorder of eye movement caused by a problem in the brain pathways that coordinate horizontal gaze. This code specifies involvement of the right eye.
Clinical signs
Typical findings include impaired adduction of the right eye with abnormal coordination of horizontal gaze. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents internuclear ophthalmoplegia affecting the right eye. It may appear in neurologic or ophthalmic evaluations when the side is clearly identified. If laterality is not documented, check documentation before coding.
Do not use for
Do not use this code for unspecified internuclear ophthalmoplegia or for other eye movement disorders without provider confirmation. Do not assume laterality from imaging alone.
Coding tip
Verify that the record states “right eye” or equivalent laterality before assigning H51.21.