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This video demonstrates what is involved when performing a prism cover test. Purpose. measuring strabismus. 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 ...
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. -do-; heavy instrument and can not keep eyelashes out of the operating field.
Prism correction. Prism lenses (here unusually thick) are used for pre-operative prism adaptation. Eye care professionals use prism correction as a component of some eyeglass prescriptions. A lens which includes some amount of prism correction will displace the viewed image horizontally, vertically, or a combination of both directions.
GIMP includes manual lens distortion correction (from version 2.4). PhotoPerfect has interactive functions for general pincushion adjustment, and for fringe (adjusting the size of the red, green and blue image parts).
Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently [ when? ] become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain ...
Almost every major camera manufacturer enables some form of chromatic aberration correction, both in-camera and via their proprietary software. Third party software tools such as PTLens are also capable of performing complex chromatic aberration appearance minimization with their large database of cameras and lens.
Loupes are used in many professions where magnification enables precision work to be done with greater efficiency and ease. Examples include surgery, dentistry, ophthalmology, the jewelry trade, gemology, questioned document examination and watchmaking. [3] Loupes are also sometimes used in photography and printing.
Based on prism-FD curves (Fig. 3b), one can find the aligning prism sP 0 that nullifies the naturally prevailing fixation disparity sFD 0. This test procedure is typically made in near vision of 40 cm, e.g. with the Mallett-unit, the Disparometer, or the Wesson card (see above).
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 ...
It is commonly suggested [citation needed] to correct perspective using a general projective transformation tool, correcting vertical tilt (converging verticals) by stretching out the top; this is the "Distort Transform" in Photoshop, and the "perspective tool" in GIMP.