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Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors. The gradient starts at the wearer's distance prescription at the top of the lens and reaches a ...
A/V: Arteriole–venue ratio BIO: Binocular indirect ophthalmoscopy BSV: Binocular single vision: BV: Binocular vision: BVD: Back vertex distance BVP: Back vertex power CD: Centration distance C/D: Cup–disc ratio CF: Count fingers vision – state distance c/o or c.o. Complains of CT: Cover test c/u: Check up CW: Close work Δ: Prism dioptre ...
Eyeglass prescription. Using a phoropter to determine a prescription for eyeglasses. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.
The most common type of corrective lens is "single vision", which has a uniform refractive index. For people with presbyopia and hyperopia, bifocal and trifocal glasses provide two or three different refractive indices, respectively, and progressive lenses have a continuous gradient. [1]
First workshop of Carl Zeiss in the center of Jena, c. 1847 Carl Zeiss Jena (1910) One of the Stasi's cameras with the special SO-3.5.1 (5/17mm) lens developed by Carl Zeiss, a so-called "needle eye lens", for shooting through keyholes or holes down to 1 mm in diameter 2 historical lenses of Carl Zeiss, Nr. 145077 and Nr. 145078, Tessar 1:4,5 F=5,5cm DRP 142294 (produced before 1910) Carl ...
The cardinal points of a thick lens in air. F, F ′ front and rear focal points; P, P ′ front and rear principal points; V, V ′ front and rear surface vertices. The cardinal points lie on the optical axis of an optical system. Each point is defined by the effect the optical system has on rays that pass through that point, in the paraxial ...
The add segment of the lens for near vision is the D-shaped area. A bifocal is a lens with two sections, separated by a line (see image to the right). Generally, the upper part of the lens is used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment.
Emmetropia is the state of vision in which a faraway object at infinity is in sharp focus with the ciliary muscle [1] in a relaxed state. That condition of the normal eye is achieved when the refractive power of the cornea and eye lens and the axial length of the eye balance out, which focuses rays exactly on the retina, resulting in perfectly sharp distance vision.