What is the Difference Between Saccades and Nystagmus?

The main difference between saccades and nystagmus lies in the nature and purpose of these eye movements:

• Saccades are quick, jerk-like eye movements that shift the center of gaze from one part of the visual field to another. They are normal eye movements that can be voluntary or involuntary and are used to detect abnormal eye movement disorders like nystagmus. Saccades range in amplitude from small movements made while reading to larger movements made while gazing around a room.
• Nystagmus is a vision condition that results in rapid, repetitive, uncontrolled side-to-side, up and down, or circular motion of the eyes. It can be caused by various factors, including damage to the vestibular system or the cerebellum. There are two types of nystagmus: jerk nystagmus, which is comprised of the drift of the eyes away from the desired target followed by a fast saccade back to the target, and pendular nystagmus, which features sinusoidal or quasi-sinusoidal eye movement trajectory.

Another difference between the two is the frequency of oscillations. The oscillations in pendular nystagmus are generally less than 10 Hz (typically 2-6 Hz), whereas the frequency of saccadic oscillations is more than 15 Hz (typically 20-40 Hz).

Comparative Table: Saccades vs Nystagmus

Here is a table comparing the differences between saccades and nystagmus:

Saccades are normal, quick eye movements that shift the center of gaze from one part of the visual field to another. They can be voluntary or involuntary and are present in both children and adults. Nystagmus, on the other hand, is an involuntary, rhythmic eye movement with a slow phase followed by a fast phase. It can be horizontal, vertical, or torsional and is usually caused by various factors such as neurological disorders, ocular disorders, medications, etc..