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Ophthalmic Lenses > Module 4 Frame Selection > Flashcards

Module 4 Frame Selection Flashcards

1
Q

What is effective power?

A

The vergence power a lens has at a position other than that occupied by the lens itself

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2
Q

For plus lenses, as the lens moves further from the face, does the effective power become stronger or weaker?

A

stronger

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3
Q

What is the formula for effective power?

A

D(E) = D(L) / (1 + dD(L))

d is + if lens is fit closer to the face than refracted and vice versa

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4
Q

For minus lenses, as the lens moves further from the face, does the effective power become stronger or weaker?

A

weaker

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5
Q

What bridge is shaped like a saddle, fits perfectly, and evenly distributes weight?

A

Saddle

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6
Q

What bridge has nose pads attached to the back side of frame, is for narrow noses, and distributes weight on the sides of the bridge?

A

Semi-saddle or modified saddle

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7
Q

What bridge has an old fashioned design where the top flares out marginally, weight is on sides, and has a very thin bridge?

A

Keyhole

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8
Q

What are the two types of bridges for metal frames?

A

Adjustable nose pads

Uni-fit bridge

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9
Q

What is a uni-fit bridge?

A

Similar to saddle bridge

For safety, children and high powered glasses

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10
Q

What is a metal saddle?

A

Weight is distributed on top of nose
John Lennon style
NOT for high powered lenses

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11
Q

What are the parts of the temples?

A 
Butt portion
Dowel hole
Shaft (shank)
Shield
Bend
Earpiece
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12
Q

What are the parts of the frame?

A 
Endpiece
Bridge
Eyewire or Rim
Shield
Nosepad
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13
Q

What are the types of temples?

A 
Skull
Convertible
Comfort cable
Riding bow
Library
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14
Q

What are Skull temples?

A

Follow contour of ear

Very popular

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15
Q

What are Library temples?

A

Held on by pressure (bow temples inward)

Half eyes, military aviators

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16
Q

What are Convertible temples?

A

Worn like skull or library temples

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17
Q

What are Riding Bow temples?

A

Plastic construction

Children’s and safety frames

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18
Q

What are Comfort Cables?

A

Metal construction

Children, safety, or tradesman

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19
Q

What is the proper frame width?

A

Equal to the widest part of the face

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20
Q

For what face type would you increase the depth of frame vertically?

A

Longer face

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21
Q

For what face type would you decrease the depth of frame vertically?

A

Shorter face

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22
Q

What type of frame aids in shortening a longer face?

A

Darker solid colored frame

Vertically gradient frame

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23
Q

What are the pros of Cellulose Acetate frames?

A

Zyl
Shell
Easily adjustable with heat

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24
Q

What are the cons of Cellulose Acetate frames?

A

Sensitive to solvent (acetone)

Dries out

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25
Q

What are the pros of Cellulose Propionate frames?

A 
Lightweight, strong, ultrathin
Used for big frames
Allergic reactions minimized
Scratch resistant
Retains colors
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26
Q

What are the cons of Cellulose Propionate frames?

A

Heat sensitive
Cold snap
Solvent sensitive

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27
Q

What are the pros of Fiber Graphite frames?

A

30% lighter than zyl
Flexible
High tensile strength
Not sensitive to solvents

28
Q

What are the pros of Polycarbonate frames?

A

Lightweight
Most impact resistant material
Safety frames or lenses

29
Q

What are the cons of Polycarbonate frames?

A

Scratches easily
Difficult to adjust
Sensitive to solvent
Cold snap lenses

30
Q

What are the pros of Optyl frames?

A

Lightweight
Keeps it’s color
Durable
Long lasting

31
Q

What are the cons of Optyl frames?

A

Must handle when hot
Memory
No water

32
Q

What are the pros of Cellulose Nitrate?

A

Good polish

zylonite

33
Q

What are the cons of Cellulose Nitrate?

A

Flammable

Banned by the FDA

34
Q

What are the pros of Monel?

A

Combo nickel (63-70%) and copper
Strong and stable
Resistant to corrosion

35
Q

What are the pros of Nickel?

A

Bends without breaking

Used with stainless steel

36
Q

What are the cons of Nickel?

A

Patients are allergic to it

37
Q

What are the pros of Nickel Silver (German Silver)?

A

Strong
Aides in long lasting adjustments
Contains >50% copper, 25% Nickel, and Zinc

38
Q

What are the cons of Nickel Silver (German Silver)?

A

Brittle

39
Q

What are the pros of Phosporous Bronze?

A

Mostly copper
Flexible
Good for thin temples

40
Q

What are the cons of Phosporous Bronze?

A

Springy

Tarnishes

41
Q

What are the pros of Stainless Steel?

A 
Strong
Thin
Noncorrosive
Good for outdoorsmen
Manganese, nickel, iron and chromium
42
Q

What are the cons of Stainless Steel?

A

Difficult to adjust

Small % of wearers are sensitive to nickel in product

43
Q

What are the pros of Titanium?

A

Corrosion-resistant

Lightweight

44
Q

What are the cons of Titanium?

A

Requires special tools to work with material

45
Q

What are the pros of Aluminum?

A

Very popular

Very few adjustments

46
Q

What are the pros of Beryllium?

A

Strong material

47
Q

What are the cons of Beryllium?

A

Costly

Rarely used

48
Q

What are the 7 basic facial shapes?

A 
Oval (can wear almost any shape frames)
Round
Triangle
Inverted Triangle
Long
Square
Diamond
49
Q

What is important when suggesting frame types based on facial shape?

A

Think opposites

50
Q

What is the boxing system?

A

System of lens measurements based on the enclosure of a lens by horizontal and vertical tangent to form a box

51
Q

What is the “A” measurement or eyewire in the boxing system?

A

The horizontal dimension of the boxing system rectangle that encloses a lens or lens opening

52
Q

What is the “B” measurement or eyewire in the boxing system?

A

The vertical dimension of the boxing system rectangle that encloses a lens or lens opening

53
Q

What is the Geometrical Center Distance in the boxing system?

A

The distance between the two geometrical centers
It can be measured from the far left side of one lens opening to the other
Also called PD and the distance between centers or DBC

54
Q

What is the Effective Diameter in the boxing system?

A

It is found by doubling the distance from the geometrical center of the lens to the apex of the lens bevel farthest from it

55
Q

What is DBL in the boxing system?

A

The distance between the two boxes when both lenses are boxed off in the frame and is measured on the frame as the distance from the inside nasal eyewire grooves across the bridge area at the narrowest point

56
Q

How much is added to the A measurement and subtracted from the DBL, if measured in plastic frame?

A

0.5 mm

57
Q

What are frame requirements for high minus wearers?

A 
Small eyewire size, large bridge size
Round corners
High index lenses
Flat or rolled bevels
Polished or rolled edges
AR
Aspheric lenses
Biconcave or blended myodisc design for very high minus
Thick rims, plastic
58
Q

What are the frame requirements for high plus wearers?

A 
Smaller eye size
Round shapes
ED + max of 2 mm
Short vertex distance
Adjustable nosepad
Aspheric design
High index lens materials
59
Q

What is the formula for front surface power?

A

D = (n(r) - 1) / r

60
Q

What is the formula for back surface power?

A

D = (1 - n(r)) / r

61
Q

What is the lensmakers equation?

A

D(N) = +(n-1)/r1 +(n-1)/r2

62
Q

What is vergence?

A

The curvature of a wavefront at a specific distance from the origin

63
Q

+ Power has what kind of relationship with focal length?

A

Inverse relationship
Longer focal length, lower power
Shorter focal length, higher power

64
Q

What is vertex?

A

The distance from the front of the eye to the back of the lens
Normally 14 mm

65
Q

How do lenses create power?

A

Curvature
Thickness
Refractive index

66
Q

How do lenses create power?

A

Curvature
Thickness
Refractive index

Ophthalmic Lenses (2 decks)

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