by admin | Oct 30, 2019 | Lens Form and Theory
Normally, eyeglasses are fitted with the optical center of the lens directly in front of the eye. If the lens is fit off-center, image displacement can occur due to induced prism. The higher the power or the further the lens is fit off-center, the higher is the...
by admin | May 5, 2010 | Lens Form and Theory
Produced by the nuclear cauldrons of stars and all matter in the cosmos, energy in the form of electromagnetic radiation permeates our entire universe. Every second of every day we are bombarded with and surrounded by electromagnetic radiation; some bounces off of our...
by admin | May 5, 2010 | Lens Form and Theory
As light rays pass through a lens with power, the rays are bent or refracted. In a lens with a plus power, the light rays converge or are refracted toward one another. The point at which the light rays converge is called the focal point and in a plus lens, is behind...
by admin | May 5, 2010 | Lens Form and Theory
It can be helpful to think of very basic lens forms in terms of prisms. Recall, as light passes through a prism it is refracted toward the prism base. Minus lenses therefore resemble two prisms apex to apex spreading light rays outward as they pass through the lens,...
by admin | May 5, 2010 | Lens Form and Theory
Prism can be used to correct vision for an individual whose eyes are not perfectly aligned as with, for example, a patient with strabismus. When the eyes are not aligned, the right and left eye see different images resulting in blurred or double vision. Sometimes the...
by admin | May 5, 2010 | Lens Form and Theory
Aspheric lenses are defined as lenses that are non-spherical. This non spherical surface encompasses all kinds of lenses from aspheric, atoric, progressive, and aphakic. So if all these lenses fall in the definition of an aspheric lens, how do we further define and...
