Ophthalmic Optics Exam II - Ophthalmic Prism

0.75 PD

One degree of angular deviation is about how many prism diopters?

compounding

The 360 degree labratory technique prism can be found by _____ two different prisms in the prescriber's method into one single prism power and direction by finding the resulting vector

resolving

The 360 deree labratory technique prism can be converted into the prescriber's method by _____ the components of the resulting vector

Rotary prism

a combination of two prims placed one on top of each other. Their bases are equal in power but with rotation they move by equal extent in opposite directions. Ie) Risley prism

add

For horizontal prism, do like bases add or subract?

subtract

For horizontal prism, do opposite bases add or subtract?

subtract

For vertical prism, do like bases add or subtract?

add

For vertical prism, do opposite bases add or subtract?

Prism Effectivity

Difference in prism power occurs when using a prism at distance vs using the prism at near. This is due to the fact that distance target incident rays are parallel, whereas near target incident rays are divergent

distant

the prism deviation is equal to the angle of rotation of the eye. Is this true for a distant or near target?

near

because incoming rays are not parallel, the prism deviation does not equal the angle of rotation of the eye. Is this true for a distant or near target?

13.5 mm

the distance to the center of rotation of the eye. Used when calculating prism effectivity while viewing a near object

Prentice's Rule

is used to describe the prismatic power of a spherical lens when the lens is displaced so that the viewer is not looking through the optical center.

base to base

A plus lens is similar to two prisms placed...

apex to apex

A minus lens is similar to two prisms placed...

Prism reference point/major reference point

the point corresponding to the patient's pupil center. Will correspond with the optical center of the lens when no prism is prescribed. If prism is prescribed, this point will not correspond to the optical center.

bifocal

Induced prism at near only can be achieved using a...

axis

Sliding a cylinder along its ____ meridian will not produce a prismatic effect because there is no power in this meridian.

power

Sliding a cylinder along its ____ meridian will produce a prismatic effect because there is power in this meridian.

perpendicular

The base direction is always ____ to the axis of a cylinder lens.

cylinder powr and decentration

prismatic power of a cylinder lens will depend on these two variables