Final exam

Question 1

What is reverse Slab-off?

Answer 1

Base down prism

Question 2

When applied to a lens, Slab-off will be on the top half or BOTTOM half of the lens?

Answer 2

Bottom

Question 3

What are the 5 Seidel Aberrations? Are they Chromatic or monochromatic?

Answer 3

MONOchromatic!
-Spherical, Coma, Oblique, Curvature of field & Distortion.

Question 4

Cr-39

Answer 4

1.498 &
58

Question 5

Polycarbonate

Answer 5

1.586 &
30

Question 6

Trivex

Answer 6

1.532 &
43-45

Question 7

Crown Glass

Answer 7

1.523 &
57

Question 8

Hi-Index 1.67

Answer 8

1.67 &
32

Question 9

what type of aberrations occurs ONLY wavelength of light?

Answer 9

MONOchromatic

Question 10

what type of aberration occurs with MORE THAN ONE wavelength of life?

Answer 10

Chromatic

Question 11

What is anisometropia?

Answer 11

2.00D or more difference in the refractive error between the right and left eyes

Question 12

What causes vertical imbalance?

Answer 12

unwanted prism

Question 13

what will the wearer experience as of result of vertical imbalance?

Answer 13

prism

Question 14

What is slab off?
Another term for Slab-off?

Answer 14

base up prism added to bottom half of a lens to correct vertical imbalance

bicentric grind

Question 15

What is the definition of lens aberration?

Answer 15

light of different wavelengths to be refracted // chromatic aberration

Question 16

Which of the lens aberrations is related the health of the eye?

Answer 16

Zernike Polynomials

Question 17

What are the chromatic lens aberrations?

Answer 17

Longitude / Lateral

Question 18

What are the all monochromatic lens aberrations ?

Answer 18

Zernike polynomials, Seidel Abberations

Question 19

Which lens abberations can be caused by WRAP AROUND frames or TITLING the lens?

Answer 19

OBLIQUE astigmatism

Question 20

what are the 4 variables of LENS DESIGNS?

Answer 20

index of refraction
lens thickness
vertex distance
lens form

Question 21

what are the 3 reasons to choose ASPHERIC LENS DESIGN?

Answer 21

improved vision, better peripheral, thinner and lighter lenses

Question 22

what is the difference between a spherical lens design and aspheric ?

Answer 22

SPHERICAL: shifter focused aberration
ASPHERIC: one focal point NO abberation

Question 23

Which REDUCES the occurrence of the lens abberation; a HIGH abbe value or low?

Answer 23

High ABBE value

Question 24

Which lens abberation can cause a PIN CUSHION or BARREL effect?

Answer 24

SEIDEL abberation

Question 25

List lens material least (BEST abbe) to most likely (WORST abbe) to cause lens abbreviation

Answer 25

Polycarbonate Hi-Index 1.67 Trivex Cr-39 Crown Glass

Question 26

If lens of 0 power (PL) is moved 10mm, how much prism is created?

Answer 26

1.0 cm

Question 27

What is the minimum amount of calculated vertical prism need to order Slab-Off for a person with Anisometropia?

Answer 27

1.50 D or more

Question 28

plus Lenticular lens

Answer 28

CENTRAL area with higher power than the sides

Question 29

Minus lenticular lens

Answer 29

LOWER power in center and higher power on Sides

Question 30

types of segmented lens

Answer 30

Double, bifocal, trifocal, round trifocal, executive

Question 31

ADDition for presbiopics? (which near)

Answer 31

Near ADD

Question 32

add to the sphere power?

Answer 32

Near power

Question 33

distance between the segs in a Double D lens?

Answer 33

13-14mm

Question 34

Greatest amount of image jump?

Answer 34

Round Segments

Question 35

Least amount of image jump?

Answer 35

Flat top segments

Question 36

Change in power and increases in cyclinder is more EVIDENT

Answer 36

HARD design

Question 37

Change in power and increases in unwanted cylinder is GRADUAL

Answer 37

soft design

Question 38

a tehcnique to use to increase thickeness to the bottom of a progressive

Answer 38

prism thinning

Question 39

where is prism read in a progressive lens?

Answer 39

the dot below the fitting cross is the location of the prism ref point

Question 40

how far apart are the laser marking on a progressive lens?

Answer 40

34mm

Question 41

what are the point of wear measurements?

Answer 41

the fitting cross

Question 42

meridian of the highest power and where the greatest thickness on a rx lens

Answer 42

△ = D d