Which neurological condition is known to cause evaporative dry eye disease due to reduced blink rate?

• A. Parkinson's disease
• B. Alzheimer's disease
• C. Diabetes mellitus
• D. Hypertension

Answer: (A)

A reduced blink rate leads to less frequent spreading of the tear film, particularly the lipid layer that reduces evaporation, so the tear film becomes unstable and evaporates more quickly. Parkinson's disease causes bradykinesia and diminished spontaneous blinking, so people with this condition often have a noticeably low blink rate. This combination produces an evaporative dry eye pattern, with quicker tear film breakup and symptoms like gritty sensation or fluctuating vision. While other conditions—like Alzheimer's disease, diabetes, or hypertension—can affect the eye in various ways, they do not produce the classic link between reduced blinking and increased tear evaporation seen with Parkinson's.