A more thorough explanation:

Definition: Nystagmus is a condition where the eyes make rapid, involuntary movements. This can happen horizontally, vertically, or in a circular motion. It can be caused by various factors such as neurological disorders, inner ear problems, or drug/alcohol use.

Example: A person with nystagmus may have difficulty reading or focusing on objects. They may also experience dizziness or vertigo.

Explanation: Nystagmus causes the eyes to move uncontrollably, which can make it hard for a person to see clearly. The rapid eye movements can also cause feelings of dizziness or disorientation.

Example: During a field sobriety test, a police officer may use the horizontal-gaze nystagmus test to check for signs of alcohol impairment. They will ask the person to follow a moving object with their eyes while keeping their head still. If the eyes make jerking movements, it could indicate intoxication.

Explanation: Alcohol can affect the brain's ability to control eye movements, leading to nystagmus. The horizontal-gaze nystagmus test is a way for police officers to detect possible alcohol impairment in a person's system.