Eye movement (sensory)

Movements of the eye that allow for visual perception and focus.

Classification
External resources

Eye movement refers to the voluntary or involuntary movement of the eyes, helping in acquiring, fixating, and tracking visual stimuli. Eye movements are essential for vision and are controlled by a complex system of muscles and nerves.

Types of Eye Movements

Eye movements can be classified into several types, each serving a distinct function in visual perception:

Saccades

Saccades are rapid, jerky movements of the eyes as they quickly shift focus from one point to another. These movements are crucial for scanning the environment and are the fastest movements produced by the human body. Saccades are used in reading and during activities that require quick shifts in attention.

Smooth Pursuit

Smooth pursuit movements allow the eyes to closely follow a moving object. Unlike saccades, smooth pursuit movements are slower and more controlled, enabling the eyes to maintain a stable image of a moving target on the retina.

Vergence Movements

Vergence movements involve the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision. These movements are essential for depth perception and are used when focusing on objects at different distances.

Vestibulo-Ocular Reflex (VOR)

The vestibulo-ocular reflex stabilizes images on the retina during head movement by producing an eye movement in the opposite direction of head movement. This reflex is crucial for maintaining a stable visual field while the head is in motion.

Optokinetic Nystagmus

Optokinetic nystagmus is a combination of a slow-phase and a fast-phase eye movement. It occurs when the eyes follow a moving object that then moves out of the field of vision, prompting a quick saccade to reposition the eyes.

Physiology of Eye Movements

Eye movements are controlled by six extraocular muscles, which are innervated by three cranial nerves: the oculomotor nerve (CN III), the trochlear nerve (CN IV), and the abducens nerve (CN VI). These muscles and nerves work in coordination to produce the various types of eye movements.

The brain regions involved in controlling eye movements include the frontal eye fields, the superior colliculus, and the cerebellum. These areas process visual information and coordinate the appropriate motor responses.

Clinical Significance

Abnormalities in eye movements can indicate neurological disorders. For example, nystagmus, an involuntary eye movement, can be a sign of vestibular system dysfunction or neurological disease. Disorders such as strabismus involve misalignment of the eyes and can affect depth perception and binocular vision.

Also see

• Vision
• Oculomotor nerve
• Vestibular system
• Strabismus
• Nystagmus

References

• Leigh, R. J., & Zee, D. S. (2015). The Neurology of Eye Movements. Oxford University Press.
• Purves, D., Augustine, G. J., & Fitzpatrick, D. (2001). Neuroscience. Sinauer Associates.