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ABO Prep > Lens Types > Flashcards

Lens Types Flashcards

1
Q

Name the Types of Bifocal Lenses?

A
  1. FT 25, 28, 35, 45
  2. Curve Top 25, 28
  3. Franklin Type (Executive)
  4. Round Seg 22, 24, 25, 28, 40
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1
Q

Name the Types of Single Vision Lenses?

A
  1. Toric
  2. Aspheric
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2
Q

Name the Types of Trifocal Lenses?

A
  1. FTT 7x25, 7x28, 7x35, 8x35, 9x35, 10x35, 12x35, 14x35
  2. Franklin Type
  3. FD Trifocal
  4. ED Trifocal
  5. RD 7x22
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3
Q

Name the Types of Invisible Multifocals?

A
  1. Blended
  2. Progressive
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4
Q

Name the Types of Cataract Lenses?

A
  1. Aspheric Lenticular SV
  2. Aspheric Lenticular Bifocal
  3. Full Field Aspheric
  4. Aspheric Lenticular Aspheric
  5. High Add Bifocals
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5
Q

Name the Types of Occupational Multifocals?

A
  1. Double RD 25
  2. Double E Segment
  3. Double FT
  4. FD Occupational Trifocal
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6
Q

What is the typical width of a Blended Bifocal?

A

28mm

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7
Q

Which other bifocal is a blended bifocal similar to?

A

a round bifocal, but just without a visible segment

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8
Q

What 3 standards need to be evaluated when making a lens material decision?

A
  1. Specific Gravity
  2. Index of Refraction
  3. ABBE Value
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9
Q

Define Specific Gravity

A

The measure of a lens material’s weight, expressed in grams per cubic centimeter

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10
Q

What does a lower Specific Gravity indicate in a lens material?

A

A lesser density and lighter material

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11
Q

Define Index of Refraction

A

the measure of a materials ability to bend light.

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12
Q

What does a larger index of refraction indicate in a lens material?

A

a greater bending of light which allows for a thinner lens

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13
Q

Define Abbe Value

A

this value represents the materials tendency to disperse visible light into it’s component colors

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14
Q

What does a lower ABBE value mean for a lens?

A

the lower the value, the greater the dispersion, meaning lower quality vision

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15
Q

What is the Specific Gravity for Trivex?

A

1.11 g/cc

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16
Q

What is the Specific Gravity for Poly?

A

1.20 g/cc

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17
Q

What is the Specific Gravity for CR-39?

A

1.32 g/cc

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18
Q

What is the Specific Gravity for Hi Index 1.60?

A

1.34 g/cc

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19
Q

What is the Specific Gravity for Hi Index 1.67?

A

1.37 g/cc

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20
Q

What is the Specific Gravity for Hi Index 1.74?

A

1.47 g/cc

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21
Q

What is the Specific Gravity for Crown Glass?

A

2.54 g/cc

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22
Q

Name the lens materials from lightest to heaviest Specific Gravity?

A
  1. Trivex
  2. Poly
  3. CR 39
  4. 1.60
  5. 1.67
  6. 1.74
  7. Crown Glass
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23
Q

Which instrument is used to measure Index of Refraction?

A

a refractometer

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24
Q

What does the measurement for Index of Refraction represent?

A

the amount of light deviation from the original path

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25
Q

What is the equation to measure index of refraction?

A

N= C/V (C divided by V)

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26
Q

In the equation to measure index of refraction, what does the C represent?

A

C = the clarity of the material.
In the case of lenses, C is clear or that of air.

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27
Q

In the equation to measure index of refraction, what does the V represent?

A

V = the vacuum or distortion of the light as it is bent.

V is the substrate (the surface) that the light is hitting

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28
Q

What is the index of refraction of CR 39?

A

1.50

29
Q

What is the index of Refraction of Crown glass?

A

1.52

30
Q

What is the index of Refraction of Trivex?

A

1.53

31
Q

What is the index of Refraction of Mid index plastic?

A

1.56

32
Q

What is the index of Refraction of Poly?

A

1.59

33
Q

What is the index of Refraction of Hi Index 1.60?

A

1.60

34
Q

What is the index of Refraction of Hi Index 1.67?

A

1.67

35
Q

What is the index of Refraction of Hi Index 1.70?

A

1.70

36
Q

What is the index of Refraction of Hi Index 1.74?

A

1.74

37
Q

In the human eye, what is the index of refraction of the Crystalline Lens?

A

1.42

38
Q

In the human eye, what is the index of refraction of the Cornea?

A

1.37

39
Q

In the human eye, what is the index of refraction of the Aqueous Humor?

A

1.33

40
Q

In the human eye, what is the index of refraction of the Vitreous Humor?

A

1.37

41
Q

What is the formula for calculating Frame Decentration?

A

(Frame PD minus Patient PD) divided by 2

42
Q

How do you measure a Frame’s PD?

A

adding the frames eye size and bridge size together

43
Q

What benefits are there to Non Glare lenses?

A
  1. There’s a 20% increase in contrast sensitivity in low light conditions.
  2. there is 2 times greater visual acuity in glare situations
  3. Lowers eye fatigue
  4. enhanced cosmetic appearance
44
Q

Name the 6 Types of Non Glare Layers

A
  1. Multilayer Non Glare
  2. Hydrophobic Non Glare
  3. Super Hydrophobic Non Glare
  4. Oleophobic Non Glare
  5. Anti Static
  6. UV Layers
45
Q

What is Multilayer Non Glare Coating?

A

AR coating that uses multiple layers of Non Glare stacked to reflect more light and reduce loss over the visible light spectrum.

46
Q

What is the Hydrophobic layer?

A

A coating layer that repels water and causes it to bead on lenses

47
Q

What determines how good a Hydrophobic layer is?

A

By testing the lenses Contact Angle. The Higher the Contact Angle, the better the Hydrophobic coating

48
Q

What is a Oleophobic non glare?

A

A coating layer that repels oil from face and hands on the lenses.

49
Q

What benefits come with using an Oleophobic non glare layer?

A
  1. Glasses stay cleaner longer
  2. Glasses are easier to clean
  3. Faster to Clean
50
Q

How are lenses made with an Anti Static coating?

A

an ion gun in the non glare chamber gives the lens a negative charge to make it so nothing clings to the lens

51
Q

What is the coating process?

A
  1. wash bath/Lens prep
  2. Mutli station Cleansing Process
  3. Dip coating can then be applied
  4. Dip coated lenses are thermally cured after Hardcoating
  5. Lenses are placed onto collets to go into the vacuum chamber for non glare coating process
  6. Lenses enter the non glare chambers and coating layers are deposited onto the lens
52
Q

What are the 2 main components of the Non Glare process?

A
  1. Hard Coat
  2. Non glare coat
53
Q

What are the two types of Hard Coat Processes?

A
  1. Dip Coating
  2. Spin Coating
54
Q

What are the two types of Non Glare Coats for Non Glare Processing?

A
  1. Vacuum Deposition
  2. Sputter Coating
55
Q

What is Dip Coating?

A

a hardcoat applied to both sides of a lens simultaneously and used primarily on high quality non glare.

56
Q

What are the benefits of Dip Coating?

A
  1. The hardcoat layer is thicker
  2. Typically has a cushion layer to prevent crazing
  3. Allows for more uniformity
  4. Allows for better Scratch Resistance
57
Q

What is Spin Coating?

A

A type of hardcoat that applies to the back surface of a lens only and is used on many multi layer stacks.

58
Q

What are the benefits of Spin Coating?

A

While the hard coat layer is a little less consistent, it -
1. allows for faster adhesion, only adding hard coat to the back of the lens and using MFR hard coat on the front of the lens
2. Allows for faster production
3. Less picky on lens substrate “approved lens listing”

59
Q

What is a Non Glare chamber used for in the coating process?

A

This is where the non glare stack is added to a lens after the hard coating layers have been applied.
This process is identical for both Spin and Dip Coatings.

60
Q

What is the benefit of Vacuum Deposition for applying a Non Glare Coat to a lens?

A

it allows broad flexibility for coating process

61
Q

What are the benefits of Sputter Coating for applying a Non Glare Coat to a lens?

A
  1. allows for compact equipment footprint(smaller equipment, size of a microwave)
  2. no crucibles
  3. fast and easy to put on
  4. can be done in office
  5. No specialized HVAC system required
62
Q

What are the downsides to Sputter Coating for applying a Non Glare Coat to a lens?

A
  1. Least durable and least consistent
  2. Warby parker, Zenni, and many online retailers use sputter
  3. The A/R liquid form that is used is from the90’s
63
Q

How are Non Glare coatings compared?

A
  1. Color
  2. Contact Angle
  3. Bayer Test
  4. COLTS Testing Service
64
Q

What effects non glare coating Color?

A

the chemical stacks and formula

65
Q

What are the typical colors of non glare coating?

A

green and blue
Though some new non glare lenses allow for additional properties due to the color. AE. Blue light coating

66
Q

What is the Bayer test?

A

an abrasion test that checks abrasion resistance compared to ISO reference lens(uncoated CR39)
The test gives you a gauge on the longevity of the lens.

67
Q

How is the Bayer test done?

A
  1. Alundum ZF-12 is added to the subject lens
  2. a side movement of 4 inches is done 150 times over 4 minutes.
  3. amount of change is then evaluated and measured by a Haze Meter
68
Q

How long are all Super Premium Non Glare Lenses good for?

A

test at 5 years, though they can only be warranted for life of the glasses rx, which is 2 years

69
Q

What is COLTS?

A

a non biased 3rd party testing service, established in 1997 that tests performance of products for all manufacturers to create standards.

ABO Prep (11 decks)

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