Saccades test - Positive, Horizontal, vertical, Normal Range, Procedure, Interpretation

Saccades Test:

• What is Saccades Test?
• Positive Saccades Test
• Horizontal Saccades
• Vertical Saccades
• Normal Range
• Procedure
• Interpretation

What is Saccades Test?

The saccades test is a clinical eye movement examination used to evaluate how quickly and accurately the eyes can jump from one target to another. Saccades are rapid, ballistic eye movements that shift visual focus between two fixed points. The test helps clinicians assess neurological function, balance disorders, vestibular problems, concussion, or oculomotor abnormalities. It is commonly used by neurologists, ophthalmologists, physical therapists, and vestibular rehabilitation specialists.

Healthy saccades are fast, symmetrical, and accurate. When abnormalities appear, they may indicate involvement of the cerebellum, brainstem, vestibular system, or cranial nerves. Because saccades rely on complex neural pathways, even small deviations can reveal important diagnostic information. The test is simple, non-invasive, and easily performed in clinics without specialized equipment.

Positive Saccades Test

A positive saccades test generally refers to an abnormal or impaired finding. This means that the eyes have difficulty performing quick, accurate jumps between targets. The clinician may observe overshooting (hypermetric saccades), undershooting (hypometric saccades), delayed initiation, slow speed, or asymmetry between the two eyes. These findings often point toward neurological or vestibular dysfunction.

A positive test is seen in conditions such as concussion, cerebellar lesions, multiple sclerosis, Parkinson’s disease, and vestibular hypofunction. Patients may also report symptoms like dizziness, blurred vision during movement, headaches, or difficulty reading. Any positive or abnormal result should prompt further neurological or vestibular assessment to determine the underlying cause.

Horizontal Saccades

Horizontal saccades evaluate the ability of the eyes to rapidly shift left and right. This movement is controlled primarily by the paramedian pontine reticular formation (PPRF) in the brainstem and coordinated by cranial nerves III and VI. During the test, the patient is asked to look quickly between two horizontal targets spaced apart at eye level.

If the eyes show delayed movement, overshooting, fatigue, or lack of coordination, horizontal saccade dysfunction may be present. This is commonly seen in vestibular disorders, brainstem lesions, and concussion-related oculomotor impairment. Precise horizontal movements are essential for reading, tracking moving objects, and maintaining clear vision during daily activities.

Vertical Saccades

Vertical saccades involve rapid up-and-down eye movements. These are controlled mainly by the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) as well as cranial nerves III and IV. During testing, the patient shifts their gaze quickly between a high and low target.

Vertical saccade abnormalities can indicate more central neurological involvement, often seen in midbrain lesions, Parkinson’s disease, progressive supranuclear palsy (PSP), and certain metabolic or neurodegenerative disorders. Vertical saccade impairment is considered more clinically significant because it often indicates deeper brain involvement than horizontal deficits.

Normal Range

A normal saccade is characterized by rapid initiation, high velocity, and precise accuracy. Typically, healthy saccades reach speeds of 300–700° per second depending on distance between targets. There should be no corrective jerks, hesitation, or noticeable lag. The eyes should land accurately on the target with minimal overshoot or undershoot.

In a normal range, horizontal and vertical saccades are symmetrical, efficient, and fatigue-free. The patient should not experience dizziness, nausea, blurred vision, or difficulty maintaining focus. Consistent abnormalities outside this normal range can signal neurological, vestibular, or oculomotor problems.

Procedure

The saccades test procedure is simple and can be performed with two fingertip targets or printed points. The clinician instructs the patient to sit upright and fix their gaze rapidly between two targets placed horizontally or vertically apart. The eyes should make quick jumps rather than smooth tracking movements.

The clinician observes accuracy, speed, latency, overshoot or undershoot, and presence of corrective movements. Both horizontal and vertical saccades are tested. The patient is also monitored for symptoms such as dizziness, headache, blurred vision, or nausea. No special equipment is required, though some clinics use computerized eye-tracking systems for more precise measurements.

Interpretation

Interpreting the saccades test involves assessing the quality of eye movements. Normal results show quick, accurate, and symmetrical movements without symptoms. Abnormal results may include slow velocity, delayed initiation, inaccurate landing, multiple corrective saccades, or asymmetry between eyes.

Different patterns suggest different pathologies: hypometric saccades may indicate cerebellar dysfunction, hypermetric saccades may point to vestibular imbalance, and impaired vertical saccades often suggest midbrain pathology. Symptoms during testing further support diagnosis. Abnormal findings should be correlated with other neurological or vestibular tests for a complete interpretation.