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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 about the causes, types, and minimization of chromatic aberration, a failure of a lens to focus all colors to the same point. Find out how achromatic lenses, diffractive optical elements, and low dispersion glasses can correct or reduce this optical defect.
Prism spectacles with a single prism perform a relative displacement of the two eyes, thereby correcting eso-, exo, hyper- or hypotropia. In contrast, spectacles with prisms of equal power for both eyes, called yoked prisms (also: conjugate prisms, ambient lenses or performance glasses) shift the visual field of both eyes to the same extent. [5]
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.
Optical aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. Learn about the different types of aberration, such as spherical, chromatic, coma, and astigmatism, and how they affect the image quality and performance of optical instruments.
Learn about different types of corrective lenses, such as glasses, contact lenses, and intraocular lenses, and how they are prescribed by eyecare professionals. Find out how to choose the right lens for your vision needs, whether it is single vision, bifocal, trifocal, progressive, or multifocal.
Learn about the optical aberrations that affect the quality of vision in the human eye, such as spherical, coma and trefoil aberrations. Find out how they are measured, corrected and influenced by factors such as age, accommodation and pupil size.
Learn about optical coatings, thin layers of material that alter the way light reflects and transmits from optical components. Find out how metal coatings such as gold, silver and aluminium are used, and how they compare with dielectric coatings.