| prism cover test | Measurement of the deviation in strabismus by the alternate cover test combined with neutralization for the deviation using prisms. (05 Mar 2000) |
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| prism vergence test | Measurement of the amplitude of fusion by placing prisms of gradually increasing power in the direction tested until diplopia occurs. (05 Mar 2000) |
| alternate cover test | A test to detect phoria or strabismus; attention is directed to a small fixation object, and one eye is covered for several seconds; then the cover is moved quickly to the other eye; if the eye moves when it is uncovered, a strabismus or phoria is present. (05 Mar 2000) |
| cover test | A test used for objective demonstration of ocular deviation in strabismus; may be performed by two methods: the cover-uncover test and the alternate cover test. (05 Mar 2000) |
| cover-uncover test | A test to detect strabismus; the patient's attention is directed to a small fixation object, one eye is covered and after a few seconds, uncovered; if the uncovered eye moves to see the picture, strabismus is present. (05 Mar 2000) |
| simultaneous | Existing or occurring at the same time: coincident, concurrent. (18 Nov 1997) |
| simultaneous contrast | The enhancement of the visual sensation of white when a white object is viewed adjacent to a black object; the black object also appears blacker as a result of the contiguity of white. Adjacent complementary colours also appear brighter; e.g., green appears a brighter green and red a brighter red if these two colours are viewed side by side. (05 Mar 2000) |
| simultaneous hermaphrodite | A type of hermaphrodite which has both male and female organs at the same time and is able to produce both sperm and eggs at the same time. Such an organism is also able to fertilize its eggs with its own sperm (self-fertilization). (09 Oct 1997) |
| simultaneous perception | A combination of two slightly dissimilar images into a single image. (05 Mar 2000) |
| refracting angle of a prism | The angle between two plane surfaces of a prism. Synonym: refracting angle of a prism. (05 Mar 2000) |
| Risley's rotary prism | A prism with a circular base that is rotated in a metal frame marked with a scale; used in examination of ocular muscle imbalance. (05 Mar 2000) |
| prism | <microscopy> A transparent body with at least two polished plane faces inclined with respect to each other, from which light is reflected or through which light is refracted. When light is refracted by a prism whose refractive index exceeds that of the surrounding medium, it is deviated or bent toward the thicker part of the prism. (05 Aug 1998) |
| prism bar | A graduated series of prism bar's mounted on a frame and used in ocular diagnosis. (05 Mar 2000) |
| prism diopter | The unit of measurement of the deviation of light in passing through a prism, being a deflection of 1 cm at a distance of 1 m. (05 Mar 2000) |
| prism illuminator | <microscopy> A 45 to ~0-degree prism interposed in the tube of a light microscope for the purpose of directing an intense beam of light through the objective onto the object. The prism illuminator utilises about one half the aperture of the objective as does the mirror illuminator with an attending loss of resolution over that obtainable with either a plane glass illuminator or a pellicle mirror. See: metallography, Nicol prism. (05 Aug 1998) |