A rhythmic oscillation of the eyes.
It can be compared to tremors in other regions of the body.
It is a disorder of ocular posture.
- Early life visual impairment
- labyrinth disorders
- cerebellar disorders
- Drug toxicity
Occurs when the individual watches a rapidly moving object (passing car).
Nystagmus is usually quicker in one direction than the other.
It is defined by its quick phase.
If the eyes jerk quickly to the left and drift back slowly towards the right this is defined as a left nystagmus.
Rarely nystagmus consists of coarse oscillations without quick and slow components, this is defined as a pendular nystagmus.
Nystagmus movements may occur in one or more planes (horizontal, vertical or rotatory).
Nystagmus may be present in all fields of gaze.
It may appear or become accentuated on deviation of the eyes, to the side or upward.
On extreme lateral gaze the normal person may show a few beats that resemble nystagmus.
- Avoid extreme movements and observe for nystagmus only within the field of full binocular vision.
Bates, Barbara. 1974. A Guide to Physical Examination. J.B. Lippincott Company, Toronto.