ICD-10 Code H51.20 – Internuclear Ophthalmoplegia, Unspecified Eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H51.20 – Internuclear ophthalmoplegia, unspecified eye
What it is
Internuclear ophthalmoplegia is a disorder of eye movement caused by impaired coordination between the eyes. The unspecified-eye code is used when the record confirms the condition but does not identify which eye is affected.
Clinical signs
Common findings include impaired adduction of one eye with nystagmus of the abducting eye. Clinical features vary; refer to documentation for laterality and associated neurologic findings.
When to use this code
Use H51.20 when the provider documents internuclear ophthalmoplegia and does not specify right, left, or bilateral involvement. It may appear in neurologic or ophthalmic evaluations where the diagnosis is stated without laterality. If the note identifies a specific eye, code that more precise option instead.
Do not use for
Do not use this code for generic diplopia, isolated nystagmus, or other ocular motility disorders without documented internuclear ophthalmoplegia. Check documentation if the laterality is specified elsewhere in the record.
Coding tip
Confirm whether the record states unspecified, right, left, or bilateral involvement before assigning H51.20.