Internuclear ophthalmoplegia digital illustration

Internuclear ophthalmoplegia Save

ICD-10 code: H51.2

Chapter: Diseases of the eye and adnexia

What is Internuclear Ophthalmoplegia?

Internuclear ophthalmoplegia (INO) is a neurological condition that affects the movement of the eyes. It occurs when there is damage to the nerve fibers that control the eye movements. INO is typically caused by a lesion or injury that affects the medial longitudinal fasciculus (MLF), a bundle of nerve fibers that connect the brainstem nuclei responsible for horizontal eye movements.

Symptoms of Internuclear Ophthalmoplegia

The most common symptom of INO is difficulty moving one eye horizontally. This is known as horizontal gaze palsy. Patients typically have difficulty looking towards the side of the lesion. In some cases, patients may also experience double vision (diplopia) when looking in the direction of the affected eye.

Causes of Internuclear Ophthalmoplegia

INO can be caused by a variety of factors, including stroke, multiple sclerosis, brain tumors, and head trauma. In some cases, the cause of the condition may be unknown.

Treatment of Internuclear Ophthalmoplegia

There is no cure for INO, but treatment options are available to manage the symptoms. In some cases, patients may be prescribed prisms or corrective lenses to help alleviate double vision. Physical therapy may also be recommended to improve eye movements and coordination. In severe cases, surgery may be necessary to correct the underlying cause of the condition.


Internuclear ophthalmoplegia can be a challenging condition to manage, but with proper treatment and management, patients can experience improved quality of life. If you or a loved one is experiencing symptoms of INO, it is important to seek medical attention promptly to determine the underlying cause and develop an appropriate treatment plan.