Fixation lets a person look specifically at an object or subject in external space and is made possible by the retinal site of highest resolution. This so-called fovea centralis represents the main direction of vision. Disorders of fixation are present, for example, in strabismus. What is fixation? By the term fixation, ophthalmology refers to the … Fixation: Function, Tasks, Role & Diseases
Human eyes are constantly in motion. In this process, the eyeballs turn consciously or unconsciously in different directions and perceive different objects arbitrarily or involuntarily. This happens through the reception of all visual stimuli by both eyes, which as a functional unit make three-dimensional vision possible. A distinction is made between vergence movements and conjugate … Saccade: Function, Tasks, Role & Diseases
When reading, the eyes do not move continuously from left to right across the text, but rather jerkily (saccadically) from gaze target to gaze target. In 15 to 20 percent of saccades, a backward saccade, regression, is performed – usually unconsciously – because the text was not fully understood or because the eyes jumped a … Regression of the Eyes: Function, Tasks, Role & Diseases
Divergence is one of the vergence movements of the eyes and corresponds to a disjunctive movement that allows fixation of objects at a distance. The opposite eye movement is convergence, which is used to fixate objects in close proximity. It, too, is a vergence movement. Divergence disorders may refer to neurological damage. What are the … Vergence Movements: Function, Task & Diseases
The trochlear nerve is the fourth cranial nerve and innervates the superior oblique muscle motor function. Together with the oculomotor nerve and the abducens nerve, it is involved in the movement of the eyeball. Double vision occurs when the nerve is paralyzed. What is the trochlear nerve? Cranial nerves are nerves with direct origin in … Trochlear Nerve: Structure, Function & Diseases
Progressive-vision contact lenses have a similar benefit for contact lens wearers as progressive-vision glasses do for eyeglass wearers: they enable sharp vision at near and far distances using the same medium. Today, these continuously technically advanced vision aids offer the same level of comfort as other contact lenses. What are varifocal contact lenses? Progressive contact … Gleaming Contact Lenses: Applications & Health Benefits
Eye movement serves all aspects of vision and is also partially controlled by reflexes triggered by self-motion, such as detecting and tracking an object. In this process, the image is placed and held in the center of the yellow spot, which is the fovea. As soon as an object moves, subsequent movements of the eye … Eye Follow Movement: Function, Task & Diseases
The term brainstem reflex includes all reflexes that, bypassing consciousness, are directed from the brainstem via efferent fibers of the corresponding cranial nerves directly to effector organs – usually specific muscles. Brainstem reflexes, which serve to protect against impending injury, play a critical role in determining brain death prior to organ removal. If only one … Brainstem Reflexes: Function, Task & Diseases
Microsaccades are minimal movements of the eyes that play a crucial role in visual perception. Without one microsaccade per second, the brain does not achieve visual perception because only microsaccades provide a shift of light on the retina. This shift is important for the retinal receptors to relay visual information to the brain. What are … Microsaccades: Function, Task & Diseases
Eye movements can be divided into active and passive movements. While active eye movements are used to record visual information, passive eye movements are used to diagnose motility disorders. What are eye movements? The human eye in cross-section showing its anatomical components. Click image to enlarge. The totality of all eye movements is also called … Eye Movement: Function, Task & Diseases
Summation is a bodily process within the visual process. The following article deals with the clarification of terms as well as the function of summation and pursues the question, what do affected persons perceive, in whom the process of summation is disturbed? What are the clinical pictures within this framework? What is summation? Summation is … Summation: Function, Tasks, Role & Diseases
In principle, the eyes can be rotated about all three possible axes of rotation in three-dimensional space, within certain limits. Parallel eye movements of both eyes, with identical rotations with respect to the axis of rotation and number of degrees, are called conjugate eye movements. They usually occur unconsciously and arise, for example, as gaze-following … Conjugate Eye Movements: Function, Task & Diseases
