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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]
Spectacles (glasses) to correct refractive errors of the eye; not invasive. Contact lenses. 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.
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.
Flat-field correction (FFC) is a digital imaging technique to mitigate the image detector pixel-to-pixel sensitivity and distortions in the optical path. It is a standard calibration procedure in everything from personal digital cameras to large telescopes.
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 types of irregular astigmatism.
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 ...
F3HP and F3/T. Initially, the F3 model with the DE-2 eye-level finder was introduced, soon followed by the popular F3HP, or High Point camera, with the DE-3 High Eyepoint prism/finder. The major advantage of this finder was that the entire viewfinder image could be seen from a distance of 2.5 cm from the viewfinder.
A Canon 7 mounted with a 50 mm lens capable of f / 0.95 A 35 mm lens set to f / 11, as indicated by the white dot above the f-stop scale on the aperture ring. This lens has an aperture range of f / 2 to f / 22. The word stop is sometimes confusing due to its multiple meanings. A stop can be a physical object: an opaque part of an optical system ...
Corrective lenses. A corrective lens is a lens worn on or before the eye. They are used to treat myopia, hypermetropia, astigmatism, and presbyopia .
In only a few years we will probably have inexpensive machines that can generate high-resolution correction maps for an individual's eyes, and machines that can quickly carve a lens from a blank, following such a correction map.