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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.
Scintillating scotoma is a common visual aura that was first described by 19th-century physician Hubert Airy (1838–1903). Originating from the brain, it may precede a migraine headache, but can also occur acephalgically (without headache), also known as visual migraine or migraine aura. [4]
Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and ...
Prism correction. Prism lenses (here unusually thick) are used for pre-operative prism adaptation. Eye care professionals use prism correction as a component of some eyeglass prescriptions. A lens which includes some amount of prism correction will displace the viewed image horizontally, vertically, or a combination of both directions.
Atmospheric optics. A colorful sky is often due to indirect sunlight being scattered off air molecules and particulates, like smog, soot, and cloud droplets, as shown in this photo of a sunset during the October 2007 California wildfires. Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of ...
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material.
Refraction occurs when light goes through a water surface since water has a refractive index of 1.33 and air has a refractive index of about 1. Looking at a straight object, such as a pencil in the figure here, which is placed at a slant, partially in the water, the object appears to bend at the water's surface.
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.
Different kinds of aberrations may have equal RMS across the pupil but have different effects on vision, therefore, RMS error is unrelated to visual performance. The majority of eyes have total RMS values less than 0.3 μm.
Fixation disparity is a tendency of the eyes to drift in the direction of the heterophoria. While the heterophoria refers to a fusion-free vergence state, the fixation disparity refers to a small misalignment of the visual axes when both eyes are open in an observer with normal fusion and binocular vision. [1]
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