What is the Difference Between Saccades and Nystagmus

The key difference between saccades and nystagmus is that saccades are normal quick jerks, like eye movements that shift the centre of gaze from one part of the visual field to another, while nystagmus is a vision condition that results in rapid, repetitive, uncontrolled side-to-side, up and down or circular motion of the eyes.

There are four normal and basic types of eye movements: saccades, smooth pursuit movements, vergence movements, and vestibular-ocular movements. Moreover, saccadic movements not fitting the normal function are a deviation from a normal condition. Therefore, abnormalities in saccades offer important clues in diagnosing a number of eye movement disorders, such as nystagmus.

CONTENTS

1. Overview and Key Difference
2. What are Saccades  
3. What is Nystagmus
4. Similarities – Saccades and Nystagmus
5. Saccades vs. Nystagmus in Tabular Form
6. Summary – Saccades vs. Nystagmus

What are Saccades?

Saccades are rapid eye movements needed to abruptly change the visual focus on an object. An example of saccadic eye movement can be seen when parents watch their children ride a merry-go-round. Saccades eye movement tests can help clinicians diagnose neurological and eye movement disorders.

In saccadic eye movement, doctors ask a patient to shift the optical focus back and forth between one pencil held in the doctor’s right hand and another in the left hand. Therefore, testing antisaccades can aid in diagnosing diseases like frontal lobe brain disease and abnormal eye movement disorders like nystagmus.

What is Nystagmus?

People with nystagmus are not able to control their eye movements. Therefore, nystagmus is a condition in which the eyes make rapid, repetitive, uncontrolled movements like up and down, side to side, or in a circle. This condition can occur in adults as well as in children. Approximately 1 in 1,000 people have nystagmus. In nystagmus, the areas of the brain that control eye movements do not work properly.

The signs and symptoms of nystagmus may include uncontrollable eye movements, shaky or blurry vision, balance problems, dizziness, light sensitivity, and nighttime vision problems.

Nystagmus can be diagnosed through vision examination, eye movement recordings, ear examination, imaging tests, CT scan, or MRI. Furthermore, treatment options for nystagmus may include wearing glasses and contact lenses, medications such as gabapentin, baclofen, and onabotulinumtoxina, eye muscle surgery, and vision correction surgery.

What are the Similarities Between Saccades and Nystagmus?

• Saccades and nystagmus are eye movements.
• Saccades can be used to detect abnormal eye movement disorders like nystagmus.
• A specialist like an ophthalmologist can identify both.
• Both can be diagnosed by vision examination.

What is the Difference Between Saccades and Nystagmus?

Saccades are normal, quick, jerk-like eye movements that shift the centre of gaze from one part of the visual field to another, while nystagmus is a vision condition that results in rapid, repetitive, uncontrolled side-to-side, up and down, or circular motion of the eyes. Thus, this is the key difference between saccades and nystagmus. Furthermore, saccades are common, whereas nystagmus is uncommon.

The infographic below presents the differences between saccades and nystagmus in tabular form for side-by-side comparison.

Summary – Saccades vs. Nystagmus

An eye movement can be voluntary or involuntary movement of the eyes. Saccades are basic eye movements that can be voluntary or involuntary. Saccades can be used to detect abnormal eye movement disorders like nystagmus. Nystagmus is involuntary. Moreover, saccades are normal quick jerk-like eye movements that shift the centre of gaze from one part of the visual field to another, while nystagmus is a vision condition that results in rapid, repetitive, uncontrolled side-to-side, up and down, or circular motion of the eyes. So, this summarizes the difference between saccades and nystagmus.

Reference:

1. “Saccade.” Encyclopædia Britannica, Encyclopædia Britannica, inc.
2. Boyd, Kierstan. “What Is Nystagmus?” American Academy of Ophthalmology.

Image Courtesy:

1. “Brain circuits for visually guided saccades” By Robert H. Wurtz – Using perturbations to identify the brain circuits underlying active vision Phil. Trans. R. Soc. B 2015 370 20140205; DOI: 10.1098/rstb.2014.0205. Published 3 August 2015 (CC BY 4.0) via Commons Wikimedia
2. “Nystagmus eye movement” By Mr Polaz – Own work (CC BY-SA 4.0) via Commons Wikimedia