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Field of view of the human eye. Peripheral vision, or indirect vision, is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the visual field is included in the notion of peripheral vision.
Rayleigh scattering causes the blue color of the daytime sky and the reddening of the Sun at sunset. Rayleigh scattering ( / ˈreɪli / RAY-lee) is the predominantly elastic scattering of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the ...
Eye examination for visual acuity. Visual acuity is a measure of the spatial resolution of the visual processing system. VA, as it is sometimes referred to by optical professionals, is tested by requiring the person whose vision is being tested to identify so-called optotypes – stylized letters, Landolt rings, pediatric symbols, symbols for the illiterate, standardized Cyrillic letters in ...
Eyeglass prescription. Using a phoropter to determine a prescription for eyeglasses. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.
To do this test, look at a cooperative person's eyes. Cover one eye of that person with a card. Have the person look at your finger tip. Move the finger around; this is to break the reflex that normally holds a covered eye in the correct vergence position. Hold your finger steady and then uncover the person's eye. Look at the uncovered eye.
Monocular vision impairment refers to having no vision in one eye with adequate vision in the other. [ 2] Monopsia is a medical condition in humans who cannot perceive depth even though their two eyes are medically normal, healthy, and spaced apart in a normal way. Vision that perceives three-dimensional depth requires more than parallax.
Eye movement can be classified according to two systems: the involvement of one or both eyes; involving one eye they may be classified as duction, and both eyes either version, if moving in the same direction, or vergence, if moving in opposite directions. [9] [10] fixational, gaze-stabilizing, or gaze-shifting.
Chromostereopsis. Blue–red contrast demonstrating depth perception effects. 3 Layers of depths "Rivers, Valleys & Mountains". Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey ...