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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]
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]
to correct refractive errors of the eye; a little invasive. Phoropter. used in refraction testing. Tonometers. used to determine the intraoccular pressure (IOP) - useful in glaucoma; video link for various types of tonometers. Speculum: to keep the eyes open during any operation. Universal eye speculum.
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 ...
Cover test. 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 ...
Subjective refraction. (Top) 0.50 confirmation set; (Middle) trial lens box, including pinhole and occluder; (Bottom) Snellen chart. Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1] It is a clinical examination used by orthoptists, optometrists and ...
Duochrome test. A duochrome test is a test commonly used to refine the final sphere in refraction (undercorrection and overcorrection), which makes use of the longitudinal chromatic aberration of the eye. Because of the chromatic aberration of the eye, the shorter wavelengths (green) are focused in front of the longer red wavelengths.
The Prentice position is an orientation of a prism, used in optics, optometry and ophthalmology. In this position, named after the optician Charles F. Prentice, the prism is oriented such that light enters it at an angle of 90° to the first surface, so that the beam does not refract at that surface. All the deviation caused by the prism takes ...
Soldier using a prismatic compass to get an azimuth. A prismatic compass is a navigation and surveying instrument which is extensively used to find out the bearing of the traversing and included angles between them, waypoints (an endpoint of the course) and direction. [1] Compass surveying is a type of surveying in which the directions of ...
Bell's phenomenon. Binasal occlusion. Biological effects of high-energy visible light. Bioptics (surgery) Bjerrum's area. Bleb (medicine) Blue field entoptic phenomenon. Botulinum toxin therapy of strabismus.