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When in lying position, the body may assume a great variety of shapes and positions. The following are the basic recognized positions: Supine position: lying on the back with the face up; Prone position: lying on the chest with the face down ("lying down" or "going prone") Lying on either side, with the body straight or bent/curled forward or ...
The first two sort of floaters may collect over the fovea (the center of vision), and therefore be more visible, when a person is lying on his or her back looking upwards. Blue field entoptic phenomenon has the appearance of tiny bright dots moving rapidly along squiggly lines in the visual field.
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 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.
Listing's law, named after German mathematician Johann Benedict Listing (1808–1882), describes the three-dimensional orientation of the eye and its axes of rotation. Listing's law has been shown to hold when the head is stationary and upright and gaze is directed toward far targets, i.e., when the eyes are either fixating, making saccades, or pursuing moving visual targets.
The trochlear solely innervates the superior oblique muscle of the eye. Together, trochlear and abducens contract and relax to simultaneously direct the pupil towards an angle and depress the globe on the opposite side of the eye (e.g. looking down directs the pupil down and depresses (towards the brain) the top of the globe).
When the head translates, the angular direction of near targets changes faster than the angular direction of far targets. [ 6 ] If the gain of the VOR is wrong (different from 1)—for example, if eye muscles are weak, or if a person puts on a new pair of eyeglasses—then head movement results in image motion on the retina, resulting in ...
Supine: lying on the back on the ground with the face up. Prone: lying on the chest with the face down ("lying down" or "going prone"). See also "Prostration". Lying on either side, with the body straight or bent/curled forward or backward. The fetal position is lying or sitting curled, with limbs close to the torso and the head close to the knees.
Pursuit eye movement can be divided into two stages: open-loop pursuit and closed-loop pursuit. Open-loop pursuit is the visual system's first response to a moving object we want to track and typically lasts ~100 ms. Therefore, this stage is ballistic: Visual signals have not yet had time to correct the ongoing pursuit velocity or direction. [9]