Prism

Question 1

Prism Diopter

Answer 1

Unit that describes the power of a prism to produce a 1 cm deviation in a ray of light at a distance of 1 meter.

Question 2

Effect of too much Base down prism

Answer 2

Causes Vertical objects to appear taller than they are. Walking straight feels like walking up hill.

Question 3

Horizontal Prism

Answer 3

• Hortizontal prism can be either Base-in or Base-out.
• Equal amount must be prescribed for each eye
• Horizontal prism can’t be greater than a total of -/+ .67 prism diopters for the two lens combined.

Question 4

Vertical prism

Answer 4

Vertical prism can be either Base-up or Base-down

Must be prescribed equally in each eye

Induced vertical prism cannot be greater than -/+ .33 prism diopters for the two lens combined

Question 5

Effect of too much Base-up prism

Answer 5

Perceive vertical objects as shorter than they are. Feels like walking downhill

Question 6

Effect of too much Base-in and Base-out Prism

Answer 6

View horizontal lines as curved

Question 7

Direction light bends in a prism

Answer 7

Light bends towards the base of a prism.

Image person sees moves in the opposite direction from the base . Retina flips the image.

Question 8

Prentice’s Rule

Answer 8

Formula to determine the amount of induced prism. How to determine how powerful induced prism is.

Prism= F x d(in centimeters)

F= power of lens
d= decentration distance in cm

Question 9

Prentice’s Rule states-

Answer 9

The power of the prism is equal to the power of the lens in Diopters, times the amount of decentration in mm, divided by 10

Prism= F x dec(mm)
__________
10

Question 10

Hypotropia

Answer 10

Eye turns down. Type of Strabism.

Question 11

Esotropia

Answer 11

Eye turns inward. Type of Strabism.

Question 12

Exotropia

Answer 12

Eye turns outward. Type of Strabism.

Question 13

Amblyopia

Answer 13

When eyes cannot work together. Results in lazy eye.

Brain cannot process 2 differently sized images from each eye.
Occationally/coninuously shuts off image from eye.

Question 14

Hypertropia

Answer 14

Eye turns upward. Type of Strabism.

Question 15

Slab off Prism

Answer 15

To correct the client from seeing double from a vertical imbalance. slab off is always done on the most minus or least plus lens. It provides base-up prism.

Question 16

Decentration Formula

Answer 16

DBC= DBL + eyesize

(DBC-PD) divided by 2= decentration per lens

DBC- distance between centers
DBL- distance between lenses

Question 17

Optical centers of a pair of Plus lenses positioned narrower than the PD creates-

Answer 17

Prism Base-in

Question 18

Optical center of a pair of Minus lenses positioned narrower than PD creates-

Answer 18

Prism Base-out

Question 19

Patient looks through Plus lenses above the optical center produces-

Answer 19

Base-down Prism

Question 20

Patient looks through Minus lenses below the optical center produces-

Answer 20

Base-down prism

Question 21

Optical center

Answer 21

Spot where light passes through a curved lens without bending. Thinnest point of a minus lens. Thickest point of a plus lens.

Question 22

Pupillary Distance

Answer 22

Distance from the center of one pupil to the center of the other pupil.

Abbreviated PD

Question 23

Base-in prism

Answer 23

Thickest part of prism toward nose

Question 24

Base-out Prism

Answer 24

Thickest part of prism toward ear

Question 25

Base-up Prism

Answer 25

Thickest part of prism is up

Question 26

Base-down Prism

Answer 26

Thickest part of prism is down

Question 27

Unwanted prismatic effect can cause

Answer 27

Headaches, double vision, Dizziness

Question 28

What is a Strabism?

Answer 28

Disorder in which eyes don’t look in exactly the same direction. Causes can be nerve injury, or dysfunction of muscles controlling the eye.