Prism II

Question 1

If prism in the OD is located in vector III, which direction would the prism be located?

Answer 1

Down and out

Question 2

If prism in the OD is located in vector I, which direction would the prism be located?

Answer 2

Up and in

Question 3

If prism in the OS is located in vector I, which direction would the prism be located?

Answer 3

Up and out

Question 4

If prism in the OD is located in vector II, which direction would the prism be located?

Answer 4

Up and out

Question 5

If prism in the OS is located in vector II, which direction would the prism be located?

Answer 5

Up and in

Question 6

If prism in the OS is located in vector III, which direction would the prism be located?

Answer 6

Down and in

Question 7

If prism in the OD is located in vector IV, which direction would the prism be located?

Answer 7

Down and in

Question 8

If prism in the OS is located in vector IV, which direction would the prism be located?

Answer 8

Down and out

Question 9

If a patient is complaining of symptoms of walking up-hill, what type of prism would they be experiencing?

Answer 9

Base down

Question 10

If a patient is complaining of symptoms of vertical objects appearing shorter, what type of prism would they be experiencing?

Answer 10

Base up

Question 11

If a myopic patient receives glasses whereby the optical center are wider than their PD, what type of prism will they experience?

Answer 11

Base in

Question 12

If a hyperopic patient receives glasses whereby the optical center are wider than their PD, what type of prism will they experience?

Answer 12

Base out

Question 13

If a myopic patient views above the optical center of the lenses, what type of prism will they experience?

Answer 13

Base up

Question 14

If a hyperopic patient views below the optical center of the lenses, what type of prism will they experience?

Answer 14

Base up

Question 15

Which of the following would represent canceling prism?
a.) 2 BU OD / 2 BD OS
b.) 2 BU OD / 2 BD OD
c.) 2 BI OD / 2 BI OS
d.) 2 BO OD / 2 BO OS

Answer 15

b.) 2 BU OD / 2 BD OD

Question 16

Which of the following would represent compounding prism?
a.) 2 BU OD / 2 BD OS
b.) 2 BD OD / 2 BD OD
c.) 2 BI OD / 2 BO OS
d.) 2 BO OD / 2 BO OS

Answer 16

a.) 2 BU OD / 2 BD OS

Question 17

A patient presents with an rx of the following:
OD -8.00 sph 6 BU / OS -8.00 sph 2 BD
After consulting with the prescriber, it is determined that it would be appropriate in order to make the glasses more cosmetically pleasing and weight balanced, it is acceptable to split the prism. What would the appropriate rx be after splitting the prism?

Answer 17

OD 8.00 sph 4 BU / OS -8.00 sph 4 BD

Question 18

Given a compound prism of 3 BI and 2 BU in the OD, what would be the resultant prism be?

Answer 18

3.61 - classic Pythagorean theorem right here

Question 18

A patient presents with an rx of the following:
OD -12.00 sph 10 BU / OS -12.25 sph
After consulting with the prescriber, it is determined that it would be appropriate in order to make the glasses more cosmetically pleasing and weight balanced, it is acceptable to split the prism. What would the appropriate rx be after splitting the prism?

Answer 18

OD -12.00 sph 5 BU / OS -12.25 sph 5 BD

Question 18

Given a compound prism of 3 BI and 2 BU in the OD, where would the resultant prism be located?

Answer 18

33.69 degrees - SohCahToa

Question 19

Where is the thickest point on a prism?

Answer 19

Base

Question 20

Where is the thinnest point on a prism?

Answer 20

Apex

Question 21

Describe what a prism does to incident white light. Include both dispersion and deviation.

Answer 21

It makes white light into a rainbow via dispersion, and it deviates the light to a steeper angle.

Question 22

When viewed through a prism that is held base down, the image of an object will be?

Answer 22

Base up

Question 23

Two rays of light that are parallel to each other before they enter a prism will do what?

Answer 23

Be deviated but stay parallel

Question 24

When a prism is held with the base to the left, the image viewed through the prism will do what?

Answer 24

Go to the right

Question 25

The factors that affect how much a ray will be deviated by a prism are what?

Answer 25

The power of the prism, the thickness of the base, and the distance from the object.

Question 26

If a pair of glasses with a plus rx is made so that the wearer is looking above the optical center of the lens, what type of prism will the wearer experience?

Answer 26

Base down

Question 27

A pair of minus lenses is cut so that the optical centers are farther apart than the wearer’s pupils. What type of prism will the wearer experience?

Answer 27

Base in prism

Question 28

When the glasses wearer looks down through the the bottom of plus lenses, what type of prism will the wearer experience?

Answer 28

Base up prism

Question 29

If the doctor asks for BO prism and the glasses rx has a minus power, where should the OC be with respect to the wearer’s pupil, and why?

Answer 29

The OC should be decentered in from the patient’s pupils, so that they are looking through base out prism

Question 30

How much prism is in effect 3mm above the OC of a 2.50 DS lens?

Answer 30

Prentice’s rule: P = hd = .3 x -2.50 = -0.75. 0.75 BU