# final Flashcards

1
Q

1
Your client’s PD is 62. The frame eyesize is 48, and the DBL is 18. When you block this lens, how much will the decentration per lens be?

A

2 mm
Remember that the formula is (DBC-PD) ÷ 2 and DBC = DBL + A measurement. The correct answer is: 2 mm (Lesson 19, Chapter 2)

2
Q

What part of the eye meshes with the optic nerve so the eye can send electrical images to the brain?

A

The retina.

3
Q

Which of these refractive errors is caused by a long eyeball that causes an image to focus in front of the retina?

A

Myopia.

4
Q

What is the job of an optician who works in orthoptics?

A

Providing therapy to help straighten the eyes.

5
Q

Which of these conditions is treated by replacing a cloudy crystalline lens?

A

Cataracts.

6
Q

Which of these measurements will help you ensure that a pair of glasses will be the correct fit for a client’s nose?

A

Bridge size.

7
Q

Which of these temple styles is best for children’s frames because the temples curl around the ear and are extremely flexible?

A

Cable temples.

8
Q

Which of these describes a positive face form?

A

The bridge is farther forward than the sides of the frame front.

9
Q

What is the geometric center distance (GCD) of a frame with the following measurements?

A= 50

B = 45

DBL = 15

ED = 52

A

65 mm

10
Q

What is the part of the retina where the vision is sharpest?

A

The fovea.

11
Q

What is the Law of Refraction?

A

Light bends toward the normal when it moves from a rarer to a denser medium.

12
Q

What is the wavelength of visible red light?

A

13
Q

O.D.: +1.75 – 2.00 x 180

What is the cylinder axis?

A

180 degrees.

14
Q

Which type of bifocal style has a segment in a small round circle?

A

A kryptok seg.

15
Q

What does a drop ball test measure?

A

The impact resistance of a lens.

16
Q

What is Prentice’s Rule?

A

Prism = lens power x decentration in centimeters.

17
Q

Which of these is an advantage of a Fresnel lens?

A

It’s thinner than a standard high-powered lens or prism.

18
Q

What is Vogel’s formula for calculating the correct base curve for a minus lens?

A

Base curve = half the spherical equivalent of the lens + 6 diopters.

19
Q

Where is the near vision sharpest in a progressive lens?

A

In the area just below the intermediate progressive corridor area.

20
Q

Which of these will you do in order to verify a pair of prescription glasses?

A

Make sure the powers, PD, lens material, base curve, adds, and tints or coatings are all correct.

21
Q

Your client’s PD is 60. The frame eyesize is 50, and the DBL is 18.

When you block this lens, how much will the decentration per lens be?

A

4 mm

22
Q

How much is 1 centimeter in inches?

A

.394 inches

23
Q

Sharon’s prescription is +1.50 -2.00 x 85. Her doctor wants to eliminate all the cylinder power. What is the spherical equivalent in Sharon’s new prescription?

A

+0.50

24
Q

Your client’s prescription is -300 +100 x 70. What numbers do you get when you transpose this prescription?

A

-2.00 -100 x 160

25
Q

What does the final number in this soft contact lens prescription specify?

-2.00 -1.25 x 90/8.6/14.2

A

The lens diameter.

26
Q

Which of these is an accurate statement about rigid gas-permeable contact lenses?

A

They can provide sharper vision than soft contact lenses do.

27
Q

What is tempering?

A

A process used to harden glass so it can be used in impact-resistant dress lenses.
Correct

28
Q

Which of these organizations created the Eyeglass I and Eyeglass II rules?

A

The FTC.

29
Q

What does a Maltese cross pattern in a polariscope tell you about a glass lens?

A

That it has been heat-tempered or hardened.

30
Q

Which layer of the cornea is the thickest layer?

A

The stroma.

31
Q

What do the superior and inferior rectus muscles do?

A

They move your eyes up and down.

32
Q

Which of the tunic layers of the eye includes the ciliary body?

A

The uveal tunic layer.

33
Q

Which of these refractive errors creates more blur in one axial direction than in another?

A

Astigmatism.

34
Q

What happens in anisometropia?

A

Each eye has a different refractive power.

35
Q

Which of these eye diseases stems from a problem with the crystalline lens?

A

Cataracts

36
Q

What will you use an Amsler grid for?

A

To diagnose and check the progression of macular degeneration.

37
Q

Which of these is the lightest and strongest metal frame material?

A

Titanium

38
Q

Which of these frame materials keeps its adjustment well and won’t corrode or get brittle?

A

Stainless steel.

39
Q

When you examine a pair of glasses, you see the numbers 48-14-120 stamped on them. What measurement does the number 120 represent?

A

The temple length.

40
Q

Which of these is a typical pupillary distance for an adult?

A

65 millimeters.

41
Q

What is a three-piece mount?

A

A style of glasses in which the temples and bridge attach directly to the lenses.

42
Q

What will you use lens axis pliers for?

A

To turn a lens so it’s aligned correctly in the frame.

43
Q

What happens to the optical center of a lens if you add two degrees of pantoscopic tilt?

A

It’s lowered one millimeter.

44
Q

What is stereopsis?

A

Depth perception.

45
Q

How will you adjust a frame if the left lens is farther out than the right?

A

Bend the left endpiece out.

46
Q

How will you decrease the pantoscopic tilt of a frame?

A

By bending both temples or endpieces up.

47
Q

What will happen to a frame if you bend the left temple down?

A

It will raise the left lens.

48
Q

Which UV rays will UV-blocking lenses protect you from?

A

UVA and UVB rays.

49
Q

What is the name of the refractive error in which the light that enters the eye focuses at two different locations within the eye?

A

Astigmatism.

50
Q

What is a lens clock used for?

A

To measure the base curve of a lens.

51
Q

Your client’s prescription is O.D. +2.75 -2.00 x 010. What do you get when you transpose it?

A

+0.75 +2.00 x 100

52
Q

Somewhere around the age of 40, people begin to lose the ability to focus on near objects. What is this refractive error called?

A

Presbyopia

53
Q

What is the power of a lens if the light rays passing through the lens focus at a point 10 cm behind the lens?

A

10 diopters.

54
Q

What is the range of wavelengths in the visible spectrum?

A

400-700 nm.

55
Q

Which tool will you use to measure the vertex distance of a frame?

A

A distometer.

56
Q

In the Boxing System, what is the B measurement?

A

The greatest vertical measurement within the box

57
Q

What frame shape looks best on a person with a base-up triangular-shaped face?

A

A frame with some heaviness at the bottom and low-mounted temples.

58
Q

What is the name of the instrument that measures corneal curvature?

A

A keratometer.

59
Q

How is a true minus powered lens typically shaped?

A

Each side of the lens is concave.

60
Q

If the bottom of a frame is too far from a person’s cheeks, what adjustment should you make?

A

Increase the pantoscopic tilt.

61
Q

What is the requirement for a lens to pass the drop ball test?

A

The lens must withstand an impact from a 5/8-inch-diameter, .56-ounce steel ball dropped from 50 inches.

62
Q

In the prescription -2.00 -1.00 x 90, what power is in the 180-degree meridian of the optical cross?

A

-3.00 diopters.

63
Q

What is the refractive index of crown glass?

A

1.523

64
Q

What is the prismatic effect when a person reads through a +4.00 diopter lens with an add of +2.00 and the person’s pupil moves down to 3 mm below the seg height? The A measurement is 40 mm, the B measurement is 50mm, and the seg height is 22 mm.

A

2.4 Δ BU

65
Q

How should you bend a frame if the right lens is higher than the left when you face the patient?

A

Bend the left temple down or the right temple up.

66
Q

How should you adjust a frame if your client’s glasses slide down the nose?

A

67
Q

What is the reading-only prescription for a prescription of -2.50 -2.00 x75, Add +2.50?

A

Plano -2.00 x 75

68
Q

A patient has a prescription of +10.00 diopters with a vertex of 12 mm. When you fit the frame on the patient, the frame sits at a vertex of 10 mm. What is the effective power of the lens when the patient wears the glasses?

A

+9.80 diopters.

69
Q

When white light goes through a prism, it’s dispersed into colors due what type of aberration?

A

Chromatic aberration.

70
Q

What would you recommend for the base curve for the following lens: -6.00 -1.00 x 090?

A

+2.75

71
Q

If the prescription for a client’s right eye is +10.00 with an exam vertex of 12 mm, and the fitted glasses have a vertex of 15 mm, which of these is an accurate statement about the effective power of the lens?

A

It has more plus power.

72
Q

What base curve would you recommend for a lens power +4.00 – 1.00 x 180?

A

+9.50

73
Q

Your client has the following prescription:

O.D. -3.50 -1.00 x 090

O.S. -4.00 -0.75 x 065

The client now wants a pair of single-vision reading glasses. What new prescription will you use?

A

O.D. -1.00 -1.00 x 090 and O.S. -1.50 -0.75 x 065.

74
Q

What is the spherical equivalent of -4.50 -1.50 x 025?

A

-5.25

75
Q

If a lab grinds a -2.50 lens so that the monocular PD is 10 mm greater than it should be, how much prismatic effect will this induce?

A

2.5 Δ BI

76
Q

What is the focal length of a +5.00 diopter lens?

A

.2 meters.

77
Q

Using a lens clock, you determine that the front surface of a lens reads +3.50 and the back surface reads +.0.50. What is the power of the lens?

A

+4.00

78
Q

Where should you mark the fitting cross of a PAL when you’re fitting a progressive lens?

A

At the pupil center.

79
Q

What is the total power of a lens if the power at 90 degrees is -2.50 and the power at 180 degrees is +2.00?

A

+2.00 -4.50 x 180

80
Q

Using a lensometer, you see that the sphere lines in the distance portion of a bifocal lens focus at -3.00. The sphere lines focus in the bifocal segment at +0.50. What is the add power of the lens?

A

+3.50

81
Q

If you don’t have a metric ruler and you measure a temple length at 6 1/2 inches, what temple length should you order?

A

165 mm

82
Q

When you’re blocking a lens, what is the decentration per lens given the following information?

PD = 60

Frame A measurement = 50, frame B measurement = 40

Distance between the lens centers = 20

A

5 mm

83
Q

When you’re blocking a right lens, how far and in which direction will you move the decentration mark given these measurements?

PD=64

DBL= 18

A measurement = 52

A

3 mm nasally.

84
Q

What is the amount of horizontal decentration of a lens, given these measurements?

Monocular PD = 29

DBC = 60

A

1 mm

85
Q

How much vertical seg height change will you make when blocking a lens for a person with a bifocal prescription who has a vertical imbalance? Here are your measurements:

A measurement = 52

B measurement = 40

Seg height desired = 14

A

6 mm

86
Q

A person’s distance PD is 2.5 inches. What is this in millimeters?

A

63.5 mm

87
Q

Given the following information about a lens, what is the horizontal decentration?

Monocular PD = 25

Eyesize = 48

DBL = 20

A

9 mm

88
Q

What is the correct MRP raise if the MRP of a lens needs to be 15 mm, the frame A measurement is 55, and the B measurement is 40?

A

5 mm

89
Q

What is the effective power of a -5.00 lens prescribed at a vertex distance of 12 mm if it sits at 10 mm from the eye?

A

-5.56

90
Q

What is the spherical equivalent of this prescription?

O.D. -5.00 -2.00 x 100

A

-6.00

91
Q

Given the following prescription, what is the total vertical imbalance when the person wearing the glasses looks down to read and the reading level of the pupils is 4 mm below the seg line?

O.D. +4.00 sphere

O.S. +2.00 sphere

B measurement = 50 mm

A measurement = 55mm

Seg height = 20 mm

A

1.8 Δ BU.

92
Q

What do you get when you transpose the following prescription?

O.S. -1.75 + 5.00 x 030

A

+3.25 -5.00 x 120

93
Q

The optical center for Fred Brown’s right lens was ground 2 mm more nasally than it should have been. What is the induced prism? The prescription is O.D. +2.50 and O.S. -5.00.

A

.5 Δ BI.

94
Q

The optical center for Mary Lake’s left lens was ground 3 mm more nasally than it should have been. What is the induced prism? The prescription is O.D. +2.50 and O.S. -5.00.

A

1.5 Δ BO.

95
Q

The lab mistakenly grinds Tom Green’s glasses so that both lenses are decentered 3 mm temporally. What is the induced prism for the right eye? His prescription is O.D. +1.50 and O.S. -4.25.

A

.45 Δ BO

96
Q

The lab mistakenly grinds Betty Palmer’s glasses so that both lenses are decentered 3 mm temporally. How much is the induced prism for her left eye? Her prescription is O.D. +1.50 and O.S. -4.25.

A

1.27 Δ BI.

97
Q

Dr. Smith prescribes glasses for Sam Jones. To achieve the prescribed prism for Sam, how much will you decenter the lens, and in which direction, for the right eye? His prescription is O.D. +3.00, 2 Δ BO and O.S. -2.00, 2 Δ BO.

A

6.7 mm outward.

98
Q

Dr. Williams prescribes glasses for Dave Johnson. His prescription is O.D. +3.00, 2 Δ BO and O.S. -2.00, 2 Δ BO. How much will you need to decenter the left lens, and in which direction, to achieve the prism prescribed?

A

10 mm inward.

99
Q

99

O.D. +2.00, 1 Δ BI

O.S. +4.00, 1 Δ BI

How much will you need to decenter the right lens, and in which direction, to achieve the prism that’s prescribed?

A

5 mm nasally.

100
Q

Louise Longmore has this prescription:

O.D. +2.00, 1 Δ BI

O.S. +4.00, 1 Δ BI

How much will you need to decenter her left lens, and in which direction, to achieve the prism that’s prescribed?

A

2.5 mm inward.