Search results
Results from the WOW.Com Content Network
Purpose. assess alignment of both eyes. The Four Prism Dioptre Reflex Test (also known as the 4 PRT, or 4 Prism Dioptre Base-out Test) is an objective, non-dissociative test used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion. [1] Through the use of a 4 dioptre base out prism ...
Individuals with nystagmus, Duane's retraction syndrome, 4th Nerve Palsy, and other eye movement disorders experience an improvement in their symptoms when they turn or tilt their head. Yoked prism can move the image away from primary gaze without the need for a constant head tilt or turn. Prism correction is measured in prism dioptres. A ...
As the alternate cover test is performed, the examiner watches the patients eye for movement. If movement is seen, the prism bar is moved to increase the power. If the 'deviation exceeds 50 prism dioptres, such that a single prism bar cannot be used', prisms can either be stacked or split . 5. Prism strength is increased until the eye under the ...
Prism adaptation. Prism adaptation is a sensory-motor adaptation that occurs after the visual field has been artificially shifted laterally or vertically. It was first introduced by Hermann von Helmholtz in late 19th-century Germany as supportive evidence for his perceptual learning theory (Helmholtz, 1909/1962). [1]
Aberrations of the eye. The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. [1] Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods ...
The prism fusion range ( PFR) or fusional vergence amplitude is a clinical eye test performed by orthoptists, optometrists, and ophthalmologists to assess motor fusion, specifically the extent to which a patient can maintain binocular single vision ( BSV) in the presence of increasing vergence demands. Motor fusion is largely accounted to ...
Prism (optics) An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides.
Lenticular printing. Close-up of the surface of a lenticular print. Lenticular printing is a technology in which lenticular lenses (a technology also used for 3D displays) are used to produce printed images with an illusion of depth, or the ability to change or move as they are viewed from different angles.
The effect also relaxes when the eyes are presented with darkness; however, experiments show that in the latter case the cyclovergence does not disappear completely straight away. Cyclovergence can also be evoked by cyclodisparity of the visual field; the cyclodisparity can be introduced by dove prisms.
The dorsal stream (green) and ventral stream (purple) are shown. They originate from a common source in visual cortex. The dorsal stream is responsible for detection of location and motion. Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs.