Which ocular sign is commonly observed in Wernicke's encephalopathy?

• A. Nystagmus
• B. Ptosis only
• C. Color blindness
• D. Cataracts

Answer: (A)

In Wernicke's encephalopathy, thiamine deficiency disrupts brain regions that control eye movements, leading to characteristic oculomotor signs. The most common ocular sign is nystagmus—rapid, involuntary eye movements that reflect dysfunction in the brainstem and cerebellar circuits that coordinate gaze. This sign often accompanies other eye movement problems like ophthalmoplegia, but nystagmus stands out as the typical, frequently observed feature.

Other eye findings like ptosis can occur if certain motor pathways are affected, but a presentation of ptosis alone isn’t the hallmark of this condition. Color vision changes and cataracts are not acute manifestations of thiamine deficiency in this context; they reflect different, non-acute processes and do not characterize the usual ocular signs of Wernicke's encephalopathy.

Recognizing nystagmus as a key sign helps prompt timely thiamine treatment, which can prevent progression and reduce the risk of permanent deficits.