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Prentice's rule is a formula to calculate the amount of prism correction in a lens based on decentration and lens power. It can be used for prescribing, tolerance control, or determining unprescribed prism in eyeglasses.
Learn how to interpret and write an eyeglass prescription that includes sphere, cylinder and axis components. Sphere and cylinder specify the power of the lenses, and axis defines the orientation of the cylinder relative to horizontal and vertical.
Learn about the different types of optical prisms, such as dispersive, reflective, beam-splitting and polarizing prisms, and how they refract, reflect or split light. Find out how prisms are made of transparent materials like glass, acrylic or fluorite, and how they can create spectra, images or polarizations.
The prism cover test (PCT) is an objective method to measure ocular misalignment or strabismus. It involves using prism bars, occluder and targets to neutralise the deviation and record the angle and base of the prism.
The appeal is clear. Tian Xiang’s shelves are packed with dried herbs, roots and flowers that make a prism of colors and textures. A wall of wooden drawers stores loose herbs; bulk bins contain ...
Learn the meaning and usage of various abbreviations in medical prescriptions, including Latin, Greek, and English terms. QD means "quaque die", meaning once daily, and is often used with a number to indicate the frequency of dosage.
An autorefractor is a computer-controlled machine that measures how light is changed as it enters a person's eye. It can provide an objective prescription for glasses or contact lenses, but it may need to be refined by a subjective refraction test.
A corrective lens is a device that improves visual perception by correcting refractive errors. Learn about the different types of lenses, such as glasses, contact lenses, and intraocular lenses, and how they are prescribed and fitted by eyecare professionals.