Search results
Results from the WOW.Com Content Network
Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex. Light will be bent towards the base and the image will be shifted towards the apex.
Prism spectacles with a single prism perform a relative displacement of the two eyes, thereby correcting eso-, exo, hyper- or hypotropia. In contrast, spectacles with prisms of equal power for both eyes, called yoked prisms (also: conjugate prisms, ambient lenses or performance glasses) shift the visual field of both eyes to the same extent.
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]
Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause. Causes include: Refractive errors; Divergence insufficiency; Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.
In studies that used standardized definitions of convergence insufficiency, investigators have reported a prevalence of 4.2–6% in school and clinic settings. The standard definition of convergence insufficiency is exophoria greater at near than at distance, a receded near point of convergence, and reduced convergence amplitudes at near.
A laboratory double-slit assembly; distance between top posts is approximately 2.5 cm (one inch). Near-field intensity distribution patterns for plasmonic slits with equal widths (A) and non-equal widths (B). In 1967, Pfleegor and Mandel demonstrated two-source interference using two separate lasers as light sources.
Reflection (physics) The reflection of Mount Hood in Mirror Lake. Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for ...
The refracting prism is made of a glass with a high refractive index (e.g., 1.75) and the refractometer is designed to be used with samples having a refractive index smaller than that of the refracting prism.
In physics, quantum tunnelling, barrier penetration, or simply tunnelling is a quantum mechanical phenomenon in which an object such as an electron or atom passes through a potential energy barrier that, according to classical mechanics, should not be passable due to the object not having sufficient energy to pass or surmount the barrier.
The latter prism needed to reduce the fixation disparity to zero is referred to as aligning prism (earlier called associated phoria). Instrumentations as the Disparometer, the Mallett-unit, or the Wesson Card differ in the type of fusion target: some use small central fixation letters, others use more peripheral fusion targets.