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Vertical prism ( base-up, or base-down) can also be added into the trial frames to separate the two red lines (This avoids confusion if the patients claim that they only see one red line). The degree of deviation and the direction (incyclo or excyclo) can be determined by the angle of rotation that causes the line images to appear horizontal ...
The vertical fusional vergence amplitude can also be measured with base up and base down prisms although the horizontal PFR is typically the main focus when testing. When performing the PFR, prism strengths are increased, placing greater demand on the vergence system, eventually resulting in a break point accompanying diplopia . [4]
The prism cover test ( PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
4 dioptre prism, either loose or prism bar; Bright lighting conditions; Method of assessment. As it is an objective test, few instructions are required to be given to the patient. The patient is asked to fixate on a target while the examiner places a 4 prism dioptre base-out prism over the patient's eye, observing the response of the fellow eye.
A regular prism is a prism with regular bases. Uniform prism. A uniform prism or semiregular prism is a right prism with regular bases and all edges of the same length. Thus all the side faces of a uniform prism are squares. Thus all the faces of a uniform prism are regular polygons. Also, such prisms are isogonal; thus they are uniform polyhedra.
Eyeglass prescription. 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. If an eye examination indicates that corrective lenses are appropriate, the ...
In geometry, a triangular prism or trigonal prism [1] is a prism with 2 triangular bases. If the edges pair with each triangle's vertex and if they are perpendicular to the base, it is a right triangular prism. A right triangular prism may be both semiregular and uniform . The triangular prism can be used in constructing another polyhedron.
Heterophoria is an eye condition in which the directions that the eyes are pointing at rest position, when not performing binocular fusion, are not the same as each other, or, "not straight". This condition can be esophoria, where the eyes tend to cross inward in the absence of fusion; exophoria, in which they diverge; or hyperphoria, in which ...