Is it true that the eye muscles can also be affected?

In rare cases, the eye muscles may be affected by ALS. Generally, eye movement remains intact throughout the course of ALS. In significantly fewer than 5% of all people with ALS, the ability to move the eyes up and down (vertical gaze) may be limited. This limitation in eye movement is usually associated with a bulbar syndrome.

In another, equally rare scenario, progressive impairment of eye movement and eyelid closure may occur. Paralysis of the eye muscles is observed in patients who are on long-term mechanical ventilation (usually via a tracheostomy) and have a very severe course of ALS. Prolonged mechanical ventilation can also lead to severe or complete loss of eye movement (ophthalmoplegia). In this situation, the visual field is restricted because the eyes cannot follow movements. Reduced blinking significantly increases the risk of the ocular surface drying out (requiring the use of an eye patch or the application of eye ointments). Overall, it can be assumed that, in the natural course of the disease—without long-term mechanical ventilation—eye movement is preserved.