PRISMS: SUM HORIZONTAL-VERTICAL AND OBLIQUE, PRISMATIC EFFECT OF SPHERO-CYLINDRICAL DECENTRATION
SUM OF 2 PRISMS
(HORIZONTAL-VERTICAL BASES)
PURPOSE
Given 2 prisms with the bases oriented in the horizontal meridian (internal or external base) or vertical (upper or lower base), the value and orientation of the prism resulting from its coupling (sum) is calculated.
DATA
Enter the power and orientation of each prism, in one or both eyes.
Press calculate.
OUTCOME
The prism resulting from the sum (power and orientation). You can also observe the quadrant in which the result is found.
You also get the resulting prism if you put it only in the right eye, only in the left eye, or evenly distributed between both eyes.
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SUM OF 2 PRISMS
(OBLIQUE PRISMS)
PURPOSE
Given 2 prisms with OBLIQUE bases, the value and orientation of the prism resulting from its coupling (sum) is calculated.
DATA
Enter the power and orientation of each prism.
Press calculate.
OUTCOME
The prism resulting from the sum (power and orientation). You can also observe the quadrant in which the result is found.
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PRISMATIC EFFECT OF SPHERO-CYLINDRICAL DECENTRATION
PURPOSE
Calculate the necessary offset of a sphero-cylindrical crystal to achieve a desired prismatic effect.
DATA
The eye.
The power of the crystal in sphero-cylindrical notation.
The desired prismatic effect (power and orientation).
OUTCOME
The necessary offset in the vertical and horizontal plane.
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BIBLIOGRAPHY
1. Optical Prisms, Clinical Applications, Susan A. Cotter, Mosby, 1996