Conjugate eye movement refers to motor coordination of the eyes that allows for bilateral fixation on a single object. A conjugate eye movement is a movement of both eyes in the same direction to maintain binocular gaze (also referred to as “yoked” eye movement). This is in contrast to

vergence A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision. When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the projec ...

eye movement, where binocular gaze is maintained by moving eyes in opposite directions, such as going “cross eyed” to view an object moving towards the face. Conjugate eye movements can be in any direction, and can accompany both

saccadic A saccade ( , French for ''jerk'') is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishi ...

eye movements and

smooth pursuit In the scientific study of vision, smooth pursuit describes a type of eye movement in which the eyes remain fixated on a moving object. It is one of two ways that visual animals can voluntarily shift gaze, the other being saccadic eye movement ...

eye movements. Conjugate eye movements are used to change the direction of gaze without changing the depth of gaze. This can be used to either follow a moving object, or change focus entirely. When following a moving object, conjugate eye movements allow individuals to stabilize their perception of the moving object, and focus on the object rather than the rest of the visual world. When changing focus, conjugate eye movements allow for the perception of a stabilized world relative to an individual, rather than the perception of the world “jumping” as the individual’s gaze shifts. Without conjugate eye movements, there would be no synchronicity of the information obtained by each eye, so an individual would not be able to willingly move their eyes around a scene while still maintaining depth perception and scene or object stability. Several centers in the brainstem are involved. Horizontal conjugate gaze is controlled by the nuclei of the

Ocular Nerve Eye movement includes the voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms (e.g. primates, rodents, flies, birds, fish, cats, crabs, octopus) to fixate, inspect and track visual objects of interes ...

, CN III, and the

Abducens nerve The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocula ...

, CN VI, the

paramedian pontine reticular formation The paramedian pontine reticular formation, also known as PPRF or paraabducens nucleus, is part of the pontine reticular formation, a brain region without clearly defined borders in the center of the pons. It is involved in the coordination of eye ...

, and the

nucleus prepositus hypoglossi The nucleus prepositus (also nucleus prepositus hypoglossi), located in the caudal pons and upper medulla oblongata, contributes to several aspects of gaze control including the Horizontal gaze nystagmus test, horizontal gaze holding system. It ...

-medial

vestibular nucleus The vestibular nuclei (VN) are the cranial nuclei for the vestibular nerve located in the brainstem. In Terminologia Anatomica they are grouped in both the pons and the medulla in the brainstem. Structure Path The fibers of the vestibular nerve ...

. Vertical conjugate gaze is controlled by the nuclei of CN III and the

Trochlear nerve The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the p ...

, CN IV, the

rostral interstitial nucleus of medial longitudinal fasciculus The rostral interstitial nucleus of medial longitudinal fasciculus (riMLF) is a portion of the medial longitudinal fasciculus which controls vertical gaze. They project to the vestibular nuclei The vestibular nuclei (VN) are the cranial nuclei ...

(riMLF), and the

interstitial nucleus of Cajal An interstitial space or interstice is a space between structures or objects. In particular, interstitial may refer to: Biology * Interstitial cell tumor * Interstitial cell, any cell that lies between other cells * Interstitial collagenase, ...

. Disorders of conjugate gaze typically consist of the inability to move one or both eyes in the desired direction, or the inability to prevent eyes from making vergence movements.

Conjugate gaze palsy Conjugate gaze palsies are neurological disorders affecting the ability to move both eyes in the same direction. These palsies can affect gaze in a horizontal, upward, or downward direction. These entities overlap with ophthalmoparesis and ophth ...

: Conjugate gaze palsies typically affect horizontal gaze, although some affect upward gaze. Few affect downward gaze. These effects can range in severity from a complete lack of voluntary eye movement to mild impairments in speed, accuracy or range of eye movement.

Internuclear ophthalmoplegia Internuclear ophthalmoplegia (INO) is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction. When an attempt is made to gaze contralaterally (relative to the affected eye), the affected eye adducts minimally ...

: Internuclear ophthalmoplegia affects horizontal gaze, such that one eye is capable of full horizontal movement, while the other is incapable of gazing in the direction contralateral to the affected eye.

One and a half syndrome The one and a half syndrome is a rare weakness in eye movement affecting both eyes, in which one cannot move laterally at all, and the other can move only in outward direction. More formally, it is characterized by "''a conjugate horizontal gaze ...

: “One and a half syndrome” also affects horizontal gaze. One eye is completely incapable of horizontal movement, while the other eye is capable of horizontal movement only in one direction away from the midline.Xue, F., Zhang, L., Zhang, L., Ying, Z., Sha, O., & Ding, Y. (2017). One-and-a-half syndrome with its spectrum disorders. Quantitative Imaging in Medicine and Surgery, 7(6), 691-697. doi:10.21037/qims.2017.12.04

References

{{reflist Anatomy