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ABO Prep > ABO Quick Facts > Flashcards

ABO Quick Facts Flashcards

1
Q

What is a Lens Clock, also known as a Geneva Lens Measure?

A

Manual device used to measure a lens Base Curve

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2
Q

Optical tools (Like a lens Clock) and gauges are Calibrated to what index?

A

1.53

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3
Q

What two other names are there for a Lensometer?

A

A Focimeter or Vertometer

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4
Q

What is a Lensometer?

A

A device that measures the focal length of a lens and translates that into power reading(the lenses prescription)

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5
Q

What is a Fused Bifocal?

A

A Bifocal lens that combines two separate indices

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6
Q

What is a One Piece Bifocal?

A

A bifocal where one index achieves add power with differing base curvatures

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7
Q

What is a lens Mechanical Center?

A

The point around which a lens is cut and edged (the center of the block)

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8
Q

What is the Geometric Center?

A

The single point in a lens at the intersection of the diagonals in the boxed shape

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9
Q

What is a lens’ Optical Center?

A

The single point on a spectacle lens through which a ray of light may pass without being deviated

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10
Q

If you’re given the Decentration and diameter of a round shape, what is the formula to measure the smallest cut out blank diameter?

A

2 x decentration plus lens diameter

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11
Q

Describe Flint Glass

A

It is Leaded, heavy, yellowish in color, and brittle

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12
Q

What is a Polariscope, also known as a Colmascope, used for?

A

Tool used to check for strain in an edged lens or to verify stress pattern in air tempered lenses

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13
Q

What is the formula for Circle of Least Confusion or Spherical Equivalent?

A

One half of the Cylinder Power plus the Sphere Power

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14
Q

Chemical Tempering uses “Ion Exchange” to do what?

A

To strengthen lenses by creating a hard outer surface

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15
Q

Which element in Photochromic glass creates the lenses changeability?

A

“Silver Halide”

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16
Q

What is a Crimping Plier used for?

A

Used to “crib” or remove excess glass from a lens blank

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17
Q

What is a Chappel Plier?

A

A cutting Plier

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18
Q

How much of incoming light does the front surface of a Crown Glass lens reflect?

A

4.28% of the incoming light

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19
Q

What are Lens Calipers used for?

A

To measure lens thickness

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20
Q

What does DBL refer to?

A

To the closest distance between two lenses

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21
Q

The velocity of light is least in which density of material? Highest or Lowest?

A

In Highest Density Material

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22
Q

What does Specific Gravity refer to?

A

A weight measurement that refers to the relationship between the density of a specific amount of lens material when compared to the density of a specific amount of Water.

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23
Q

What is Chromatic Aberration?

A

The breaking up of white light into its component parts.

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24
Q

What is an Axial Ray?

A

A name for the ray that passes through a lens without being refracted.

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25
Q

Will a glass rod immersed in a medium of the same index of refraction be Visible or Invisible?

A

Invisible

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26
Q

To get a ballpark “Best Base Curve”, what should you do?

A

Add +4.00 to plus powers and +8.00 to minus powers

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27
Q

What is a Retinoscope?

A

A tool used to measure refractive power in the eye

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28
Q

What is a Tonometer?

A

measures intraocular pressure in the eye

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29
Q

What is an Ophthalmoscope?

A

A tool used to view inside the eye

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30
Q

What do Cycloplegics do?

A

Inhibit accommodation

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31
Q

What is a Scotoma?

A

a blind spot, an area of retinal vision loss

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32
Q

Where does the fusion of two ocular images take place?

A

in the brain

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33
Q

What are Rods?

A

a layer of cells on the retina for peripheral vision, black and white vision, and night time viewing.

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34
Q

What are Cones?

A

a layer of cells on the retina for color vision and for most acute vision.

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35
Q

What is a Snellen chart used for?

A

to test distance vision acuity

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36
Q

What is a Jaeger Chart used for?

A

to test near vision acuity ( J4 or J2)

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37
Q

What do Mydriatic eye drops do?

A

Dialates the pupil

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38
Q

The 20/200 line on the Snellen Chart is how tall?

A

8.87 cm tall

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39
Q

What is Kerataconus?

A

A cone shaped deformity of the cornea

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40
Q

What is the Limbus?

A

The junction between the cornea and the sclera

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41
Q

What is the Canthus?

A

The corner of the eye where the lids meet

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42
Q

Define Nystagmus

A

An involuntary, rapid and repetitive movement of the eyes often associated with light sensitivity, or photophobia

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43
Q

Define Photophobia

A

Eye discomfort in bright light

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44
Q

Define Glaucoma

A

An eye disease characterized by a buildup of inter ocular pressure.

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45
Q

Define Aphakic Patients

A

Patients who have had their crystalline lens removed.

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46
Q

Define Psuedo Aphakic patients

A

Patients who have had an implant to replace the crystalline lens

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47
Q

What is the average size of a normal pupil in normal lighting?

A

3 to 5 mm

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48
Q

Define Ptosis

A

a drooping lid

49
Q

How is a Ptosis corrected?

A

using a Ptosis Crutch

50
Q

How many extrinsic muscles account for the movement of the eye?

A

6

51
Q

Aphakes can benefit greatly by using which type of lens?

A

a progressive variable focus lens

52
Q

Define Chiasm

A

the point where the optic nerves from each eye are combined.

53
Q

Define Antimetropia

A

condition characterized by Rx’s with opposite signs (- in one, + in the other)

54
Q

Define Anisometropia

A

Vertical prismatic imbalance characterized by unequal power and prismatic effect at the reading level

55
Q

Define Anisiekonia

A

dissimilar image size from eye to eye due to uneven magnification

56
Q

The eye is most sensitive in which area of the color spectrum?

A

yellow/green

57
Q

To whom are trifocals prescribed for?

A

for Advanced Presbyopes

58
Q

Define Tropia

A

A definite deviation of the eye

59
Q

Define Phoria

A

A tendency for the eye to deviate

60
Q

Eso =

A

In

61
Q

Exo =

A

Out

62
Q

Hyper =

A

Up

63
Q

Hypo =

A

Down

64
Q

Do Photochromic lenses have more or less reaction in warm weather?

A

Less Reaction

65
Q

Do Photochromic lenses have more or less reaction in cold weather?

A

More Reaction

66
Q

What are Half Round Pliers?

A

A tool used for American style nosepad Arm adjustment

67
Q

What are Box Pliers?

A

a tool used for European style nosepad arms

68
Q

What is another name for Bicentric Grinding, and what is it used for?

A

Slab-off. used to correct vertical imbalance

69
Q

How many optical centers does a Standard Bifocal have after it is fabricated, and how many can be found in a Lensometer?

A

3 total optical centers, only 2 can be found in a lensometer

70
Q

What are Absorptive lenses and how are they formed?

A

Colored glass lenses formed by adding metal oxides to the glass

71
Q

Which color is the best absorber of Infrared light in a glass lens?

A

Green glass lens

72
Q

What are the two types of Dropball Tests on Lenses?

A

5/8ths inch steel ball for Dress Safety, and 1 inch steel ball for Industrial Safety.

73
Q

What should the total weight of the Dropball Testing apparatus be?

A

No less than 27 pounds

74
Q

Who invented the first Bifocal Lens?

A

Benjamin Franklin

75
Q

The back surface of a progressive is spherical or aspheric?

A

Spherical

76
Q

The front surface of a progressive is spherical or aspheric?

A

Aspheric

77
Q

Which type of prism is easiest to tolerate at the near point?

A

Base In Prism

78
Q

What does a wearer experience when a lens has excessive Base Down Prism?

A

Makes floor or horizontal expanses seem concave and feel like they’re standing in a bowl. Vertical objects may seem taller and they may feel like they’re walking uphill

79
Q

What does a wearer experience when a lens has excessive Base Up Prism?

A

causes the floor or other horizontal expanses to seem convex as they feel like they are standing on a hill. Vertical objects may seem shorter and the wearer feels like he is walking downhill

80
Q

What does a wearer experience when a lens has excessive Base In or Base Out Prism?

A

Cause the wearer to see horizontal objects as high at one end and low on the other. The too high side will always be towards the apex

81
Q

What can be used to neutralize vertical imbalance at near?

A

use dissimilar segments like Exec/Ultex

82
Q

What is the Listings Plane?

A

the imaginary optical plane lying in the X and Y axis

83
Q

Define Amblyopia

A

also known as Lazy eye. it’s the loss of vision without any apparent defect to the eye. Generally develops in just one eye(though there are exceptions) and is caused by abnormal visual development early in life.

84
Q

What does Ferrous Oxide do to lenses?

A

Gives lenses a green color and UV as well as Infrared absorption

85
Q

Dispersion is categorized by what?

A

By Abbe Number, or as it is commonly known by Constringency Value or Nu Value.

86
Q

How much does the 5/8th inch standard Dropball weigh?

A

0.56 Ounces

87
Q

Bifocal add power is equal to what?

A

to the difference between the back vertex measurement of the distance and near lensometer readings.

88
Q

Which lens design delivers the least off-axis viewing blur?

A

a corrected curve “Best form” lens design

89
Q

Are Impact Resistant lenses unbreakable?

A

NO

90
Q

What are the parameters of the visible spectrum?

A

Approximately from 400 to 750 nm

91
Q

The eye as an optical system generates approximately how much refractive power?

A

60 diopters

92
Q

How much of the refractive power in an eye is from the cornea?

A

40 diopters

93
Q

Plus powered lenses moved farther away from your eyes make the lens strength stronger or weaker?

A

Stronger

94
Q

Plus powered lenses moved closer to your face make the lense strength stronger or weaker?

A

Weaker

95
Q

Minus powered lenses moved farther away from your face make the lense strength stronger or weaker?

A

Weaker

96
Q

Minus powered lenses moved closer to your face make the lense strength stronger or weaker?

A

Stronger

97
Q

Name the 4 standard Temple Lengths

A

5 1/4 in = 135 mm
5 1/2 in = 140 mm
5 3/4 in = 145 mm
6 in = 150 mm

98
Q

When fitting a child with a segmented bifocal, it is common to do what?

A

Split the Pupil

99
Q

When given multiple lens materials, how would you determine which is the thinnest?

A

choosing the lens with the highest index

100
Q

What is the best lens for water activities?

A

a polarized lens

101
Q

Does Medicare cover cataract surgery?

A

Yes

102
Q

Optyl frames require a lens to be edged how many mm over the marked eyesize?

A

1/2 mm

103
Q

Does Optyl material stretch or shrink?

A

It will stretch somewhat, but it will NOT shrink

104
Q

The safest lens in all circumstances is what?

A

Polycarbonate

105
Q

Any questions involving prismatic effect due to wide or narrow pd’s first require location of the power at what angle?

A

180 degrees

106
Q

Any questions involving prismatic imbalance at the reading level first require location of the power at what angle?

A

90 degrees

107
Q

Snell’s Law deal’s with what 2 things?

A

Reflection and refraction

108
Q

An Un-AR coated glass or plastic lens will reflect what percentage of light? What percentage of light will it transmit?

A

reflect 8% and transmit 92%

109
Q

What is the focal length of a 1 Diopter lens?

A

1 Meter

110
Q

How much will a 1 diopter prism deviate a ray of light at a distance of 1 meter?

A

1 cm

111
Q

What is the Radius of Curvature of a 1 diopter lens?

A

530 mm

112
Q

Formula to measure Focal length in meters

A

1 divided by dioptric power

113
Q

What is 1 Meter in cm, mm, and Inches?

A

100 cm, 1000 mm, 39.37 in

114
Q

Prentice Rule

A

Prismatic effect = (distance move x dioptric power) divided by 10

115
Q

Name the 5 types of Astigmatism

A

Simple Myopic, Simple Hyperopic, Compound Myopic, Compound Hyperopic, and Mixed

116
Q

How many years must a patient records for impact resistance be kept?

A

3 years

117
Q

How do you check the amount of prism that is ground into a SLAB OFF lens?

A

using a Lens clock, place lens clock parallel above the Slab line and measure the BC, then turn the lens clock perpendicular with the center pin centered on the Slab line and measure that BC. then subtract the two numbers to get the difference

118
Q

What is a Meniscus Lens?

A

a crescent shaped lens, one side concave and one side convex, with one side having a 6 base curve

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