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A **toric** lens is a lens with two different powers in two orientations perpendicular to each other. One of the lens surfaces is shaped like a "cap" from a torus (see figure at right), while the other one usually is spherical . **Toric** lenses are primarily used in eyeglasses , contact lenses

**wikipedia.org** | 2011/7/19 23:35:06

In algebraic geometry , a **toric** variety or torus embedding is a normal variety containing an algebraic torus as a dense subset , such that the action of the torus on itself extends to the whole variety. Contents 1 The **toric** variety of a fan 2 Morphisms of **toric** varieties

**wikipedia.org** | 2010/9/28 6:40:09

A corrective lens is a lens worn in front of the eye , mainly used to treat myopia , hyperopia , astigmatism , and presbyopia . Glasses or "spectacles" are worn on the face a short distance in front of the eye. Contact lenses are worn directly on the surface of the eye. Intraocular lenses

In mathematics , a **toric** manifold is a topological analogue of **toric** variety in algebraic geometry . It is an even-dimensional manifold with an effective smooth action of n-dim compact torus which is locally standard with the orbit space a simple convex polytope . The aim is to do combinatorics

**wikipedia.org** | 2010/9/25 2:32:17

A **toric** section is an intersection of a plane with a torus , just as a conic section is the intersection of a plane with a cone . Contents 1 Mathematical formulae 2 Spiric sections 3 Villarceau circles 4 General **toric** sections [ edit ] Mathematical formulae In general

**wikipedia.org** | 2010/9/25 17:31:59

A contact lens (also known simply as contacts for a pair) is a corrective , cosmetic , or therapeutic lens usually placed on the cornea of the eye . Leonardo da Vinci is credited with describing and sketching the first ideas for contact lenses in 1508, but it was more than 300 years later

An intraocular lens (IOL) is an implanted lens in the eye , usually replacing the existing crystalline lens because it has been clouded over by a cataract , or as a form of refractive surgery to change the eye's optical power . It usually consists of a small plastic lens with plastic side

price. [ 3 ] Other subcategories of contact lenses include bifocal (for correcting presbyopia), **toric** (for correcting astigmatism), and corneal reshaping contact lenses. [ 2 ] [ edit ] General risks Keratitis , or an inflammation of the cornea In general, contact lens use is thought

price. [ 3 ] Other subcategories of contact lenses include bifocal (for correcting presbyopia), **toric** (for correcting astigmatism), and corneal reshaping contact lenses. [ 2 ] [ edit ] General Risks Keratitis , or an inflammation of the cornea In general, contact lens use is thought

There is no national standard or system for railroad signaling in North America. Individual railroad corporations are free to devise their own signaling systems as long as they uphold some basic regulated safety requirements. Due to the wave of mergers that have occurred since the 1960s it