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Ophthalmic Optics > Block 1 > Flashcards

Block 1 Flashcards

1
Q

Instrument to measure sphere, cyl power and axis, add power, and prism power and direction

A

Lensometry

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2
Q

Does lensometry measure the front or back vertex power of lens

A

Back

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3
Q

What type of telescope is a lensometer

A

Keplarian

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4
Q

How to find the -0.25D cyl axis

A

Bracket

- move in 1 direction until it breaks, then same in the other and put the number in the middle

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5
Q

Do spec Rx expire

A

No, unless a date is specified

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6
Q

Do CL Rx expire

A

Yes, = 1 yr

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7
Q

Do you have to set the axis dial to 180 before reading glasses

A

No

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8
Q

When to use the green background while reading

A

Clear or lightly tinted specs

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9
Q

When to use the orange background while reading

A

Dark tint or sunglasses

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10
Q

What should you always do before putting the glasses in the read

A

Set power to 0
Set prism to 0
Focus the eye piece

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11
Q

Different kinds of multifocal lenses

A

Progressive
Bifocal
Trifocals

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12
Q

What are multifocal lenses

A

Have 2 or more lens powers

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13
Q

Who wears multifocal lenses

A

Usually over 40

Also, young children with focusing problems

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14
Q

If kids have focusing problems, which type of multifocal lenses are typically used

A

Usually bifocals, because progressives are harder to adjust to

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15
Q

Good for people with issues such as lazy eye; have no areas of distortion

A

Lined multifocal so

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16
Q

How to read the add power in a strong Rx (> +/- 5D)

A

Flip frames to where the temples are facing you

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17
Q

Progression of lens power from full distance correction at the top to full reading at the bottom

A

PAL (progressive)

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18
Q

Plus in the middle of progressive

A

Fitting point

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19
Q

Where should the fitting point sit

A

Center of pupil

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20
Q

Dot below plus sign on progressive

A

Prism reference point

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21
Q

Optical center of PAL

A

Prism reference point

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22
Q

Which side of progressive has the add power

A

Temporal side

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23
Q

Triangular shape that change the direction of light

A

Prism

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24
Q

Which way does light bend in the prism

A

Toward base

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25
Q

Which way is the image formed through the prism

A

Apex

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26
Q

How to determine how much prism is in lens

A

Where the single line and middle of triple lines intersect

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27
Q

Unit that describes the power of a prism to produce a one cm deviation at a distance of 1m from the lens

A

Prism diopter

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28
Q

2 ways prism can be incorporated

A
  • ground in

- induced

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29
Q

Grinding he surface of a lens during manufacturing

A

Ground in prism

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30
Q

Decentering the optical center to utilize the prismatic properties of sphere-cyl lens

  • prentice rule
A

Induced prism

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31
Q

What is prentice rule

A

Prism D = P x d(cm)

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32
Q

If you move the lens around, the intersection will stay off center

A

Ground in prism

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33
Q

the only way that the mires can be centered is if the lens is decentered

A

Induced prism

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34
Q

What vertical prisms cancel out

A

BU and BU in both
Or
BD and BD in both

35
Q

What horizontal prisms cancel out

A

BI and BO

36
Q

When do you use the prism compensating device

A

If more than 5 prism D

- cant see both sets of mires

37
Q

What do the 3 numbers on a temple or bridge stand for

A

Eye size - bridge width - temple length

38
Q

Normal range for eye size

A

40-62 mm

39
Q

Normal range for bridge

A

14-24 mm

40
Q

Normal range for temple length

A

120-150 mm

41
Q

Why are the eye-bridge-temple listed on the frame

A

They are set numbers, cant be changed

- important for frame fit and sizing

42
Q

Frame measurements: A

A

Horizontal width

43
Q

Frame measurements: B

A

Vertical height

44
Q

Frame measurements: DBC

A

Distance between centers

45
Q

Frame measurements: DBL

A

Distance between lenses

46
Q

Frame measurements: ED

A

Effective diameter

- 2 times the longest radius

47
Q

Frame measurements: OTL

A

Length of temple

48
Q

How different is the near PD from far PD

A

Usually about 2 mm smaller in each eye

49
Q

How is pupillary distance measured

A

Pupilometer

50
Q

Which direction of decentration if pt PD>frame PD

A

Move out

51
Q

Which direction of decentration if frame PD > pt PD

A

Move in

52
Q

Distance between bottom edge of lens and top of segment

A

Seg height

53
Q

Distance between datum line (center of lens) and top of bifocal/trifocal

A

Seg drop

54
Q

Distance the center of the near segment is moved laterally for the OC

A

Seg inset

55
Q

Typical segment height of bifocal

A

Top of lower lid

56
Q

Typical segment height of trifocal

A

Lower lid margin

57
Q

Typical segment height of progressive

A

Pupil center

58
Q

Determines the smallest possible lens blank for a given frame and PD combo

A

MBS = (DBC - PD) + ED

59
Q

Final step in the manufacturing of eyewear

A

Inspection process

60
Q

System of standards and tolerances used to verify eyewear

A

Inspection process

61
Q

Formula for finding the power in a certain meridian question

A

Sphere + Cyl(sin^2theta)

  • theta being the difference between the axis of Rx and of the meridian in ?
62
Q

Surfacing of a portion of a lens so as to add a second optical center

A

Slab off

63
Q

Formula for vertical imbalance

A

((Lens P @90) x (distance from OC)) / 10

64
Q

Distance from back surface of specs to apex of cornea

A

Vertex distance

65
Q

As you move closer to the eye, how does the CORRECTION change

A

Rx get more PLUS the closer you get

66
Q

Formula for vertex distance

A

New P = (old P)/(1 - (d in m x old P)

D: positive for moving closer to eye, negative for moving away from the eye

67
Q

How to calculate the vertex distance/new power with a sphere-cyl lens

A

Do the formula for both the sphere and the cyl powers

68
Q

Tool used to measure the D power of lens

A

Lens clock

69
Q

What refractive index is the lens clock designed for

A

1.53

70
Q

When there is a difference in the front and back, how do you find the nominal power

A

Add the 2 values together

71
Q

Which part of the lenses to the thickness calipers measure

A

The thinnest part

72
Q

Minus lens –> where is thickness measured

A

Center

73
Q

Plus lenses –> where to check thickness

A

The edge

74
Q

Types of adjustment tools

A

Pliers, screwdriver set, drill mount kit

75
Q

Tool used to adjust a plastic frame

A

Hot air frame warmer

76
Q

Off-face check

A 
X-ing
Temple spread
Temple fold angle
Nose pads
Faceform/wrap
77
Q

6 steps to proper adjustment

A 
Wearing position 
Nose pads
Horizontal alignment
Pantosopic tilt
Vertex distance/wrap
Temple bend
78
Q

Best frame for high Rx

A

Full frame

79
Q

Good for pt that doesn’t take glasses on and off often

A

Rimless

80
Q

Hybrid of semi-rimless and full

A

Inline

81
Q

2 most common metal frame types

A

Monel

Titanium

82
Q

2 components of monel

A

Nickel and copper

83
Q

Most common plastic frame material

A

ZYL - zylonite

84
Q

Common allergies to frame materials

A

Nickel and silicone

Ophthalmic Optics (1 decks)

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