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The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have significantly improved the accuracy with which the ...
A toric IOL is a type of toric lens used to correct preexisting corneal astigmatism at the time of cataract surgery. [20] Astigmatism can also be treated with limbal relaxing incisions or an excimer laser procedure. [21] [22] About 40% of Americans have significant astigmatism and thus may be candidates for a toric IOL. [22]
Toric lens surface as "cap" (top-right) from a torus (here with R = 1.2 r). A toric lens is a lens with different optical power and focal length in two orientations perpendicular to each other. One of the lens surfaces is shaped like a "cap" from a torus (see figure at right), and the other one is usually spherical .
Toric Markers are markers made for marking on the outside of the cornea or sclera part of the eye. They are designed with semi-sharp or pointed line or dot patterns. There are two kinds of markers - Pre-Op markers and Intra-Op markers. [1] Pre-Op markers: these are used before the patient lies down for surgery.
The toric variety constructed from a fan is necessarily normal. Conversely, every toric variety has an associated fan of strongly convex rational cones. This correspondence is called the fundamental theorem for toric geometry, and it gives a one-to-one correspondence between normal toric varieties and fans of strongly convex rational cones. [2]
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 an n {\displaystyle n} -dimensional compact torus which is locally standard with the orbit space a simple convex polytope .
A special case of a toric section is the spiric section, in which the intersecting plane is parallel to the rotational symmetry axis of the torus. They were discovered by the ancient Greek geometer Perseus in roughly 150 BC. [2] Well-known examples include the hippopede and the Cassini oval and their relatives, such as the lemniscate of Bernoulli.
In algebraic geometry, a toric stack is a stacky generalization of a toric variety. More precisely, a toric stack is obtained by replacing in the construction of a toric variety a step of taking GIT quotients with that of taking quotient stacks. Consequently, a toric variety is a coarse approximation of a toric stack.