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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.
A Fresnel rhomb is an optical prism that introduces a 90° phase difference between two perpendicular components of polarization, by means of two total internal reflections. If the incident beam is linearly polarized at 45° to the plane of incidence and reflection, the emerging beam is circularly polarized , and vice versa.
Also, plastic prisms (Fresnel prisms) can be attached to eyeglasses of a diplopic patient, allowing for alignment of vision from both eyes in the affected direction, but are often problematic if the degree of muscle weakness, and therefore ocular misalignment, fluctuates frequently.
A Fresnel lens ( / ˈfreɪnɛl, - nəl / FRAY-nel, -nəl; / ˈfrɛnɛl, - əl / FREN-el, -əl; or / freɪˈnɛl / fray-NEL [1]) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.
In a memoir read in September 1822, Fresnel announced that he had verified Brewster's diagnosis more directly, by compressing a combination of glass prisms so severely that one could actually see a double image through it.
Higher power Fresnel ("stick-on") prisms are commonly employed because they are thin and lightweight, and can be cut and placed in different positions on a spectacle lens. Peripheral prism spectacles expand the visual field of patients with hemifield visual defects and have the potential to improve visual function and mobility. [8]
The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media.
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. [1] These optically anisotropic materials are described as birefringent or birefractive.
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural ...
Stereopsis. Stereopsis is the component of depth perception retrieved by means of binocular disparity through binocular vision. [1] It is not the only contributor to depth perception, but it is a major one. Binocular vision occurs because each eye (left and right) receives a different image due to their slightly different positions in one's head.