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Neurology, ophthalmology. Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. [ 1 ] Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary.
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
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
A cover test or cover-uncover test is an objective determination of the presence and amount of ocular deviation. It is typically performed by orthoptists, ophthalmologists and optometrists during eye examinations. The two primary types of cover tests are: the alternating cover test. the unilateral cover test (or the cover-uncover test).
Frequency. ~2% (children) [3] Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. [2] The eye that is pointed at an object can alternate. [3] The condition may be present occasionally or constantly. [3] If present during a large part of childhood, it may result in amblyopia, or lazy ...
Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve), which is responsible for causing contraction of the lateral rectus muscle to abduct (i.e., turn out) the eye. [1] The inability of an eye to turn outward, results in a convergent strabismus or esotropia of which the ...
In order to see a clear image, the eye must focus rays of light on to the light-sensing part of the eye - the retina, which is located in the back of the eye.This focusing - called refraction - is performed mainly by the cornea and the lens, which are located at the front of the eye, the anterior segment.
Prism (optics) A familiar dispersive prism. 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 ...