Search results
Results From The WOW.Com Content Network
Oculomotor apraxia (OMA) is the absence or defect of controlled, voluntary, and purposeful eye movement. [1] It was first described in 1952 by the American ophthalmologist David Glendenning Cogan. [2] People with this condition have difficulty moving their eyes horizontally and moving them quickly.
For light to converge to a perfect point, the wavefront emerging from the optical system must be a perfect sphere centered on the image point. The distance in micrometers between the actual wavefront and the ideal wavefront is the wavefront aberration, which is the standard method of showing the aberrations of the eye.
A core aspect of studies in this area is the division of eye movements into the rapid movement of the eyes , and the focus of the eyes on a point (fixations). Several factors can influence eye movement in scene viewing, including the task and knowledge of the viewer (top-down factors), and the properties of the image being viewed (bottom-up ...
The vestibulo-ocular reflex is a reflex eye movement that stabilizes images on the retina during head movement by producing an eye movement in the direction opposite to head movement in response to neural input from the vestibular system of the inner ear, thus maintaining the image in the centre of the visual field. For example, when the head ...
Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.
An eye movement shifts the orientation of the coil to induce an electric current, which is translated into horizontal and vertical eye position. The second technique is an eye tracker . This device, while somewhat more noisy, is non-invasive and is often used in human psychophysics and recently also in instructional psychology.
The eye develops in utero during the first three months of pregnancy, and a gap called the choroidal fissure appears at the bottom of the stalks that eventually form the eye, the AAO explains.
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation, among others.