Definition
Pendular nystagmus is a form of involuntary eye movement characterized by oscillations of equal speed in both directions, resembling a pendulum's motion. It can affect one or both eyes and is typically seen in neurological or sensory disorders.
Key Features
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Movement Characteristics:
- Oscillations are sinusoidal, smooth, and of equal velocity in both directions.
- Unlike jerk nystagmus, there is no fast or slow phase.
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Direction:
- Movements can be horizontal, vertical, torsional, or a combination.
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Amplitude and Frequency:
- Amplitude: Can range from fine (small movements) to coarse (large movements).
- Frequency: Often slow, but varies depending on the underlying cause.