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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.
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.
Glasses are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes. They can be used for vision correction, eye protection, cosmetic purposes, or viewing specific visual information.
Vertex distance is the distance between the back surface of a corrective lens and the front of the cornea. It affects the optical properties and power of the lens relative to the eye. Learn how to calculate and adjust vertex distance for glasses and contacts.
Bifocals are eyeglasses with two distinct optical powers, commonly prescribed to people with presbyopia. Benjamin Franklin is generally credited with the invention of bifocals, but there is some evidence that others may have come before him.
Learn about the physiology and perception of vision in humans and other organisms, as well as the devices and methods to correct or enhance vision. Find out how optics and vision are related to optometry, ophthalmology, and neuroscience.
Learn about the origins and development of optics from ancient times to modern days. Explore the contributions of Greek, Roman, Islamic, and European scholars to the fields of geometrical, physical, and physiological optics.