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Ophthalmic optics 2 > Exam 1 shuffled > Flashcards

Exam 1 shuffled Flashcards

(104 cards)

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1
Q

The ___ the index of refraction, the greater the glare and reflections

A

The higher the index of refraction, the greater the glare and reflections

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2
Q

Which frame material has issues with “gapping”

A

aluminum

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3
Q

What is the Abbey for polycarbonate?

A

30

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4
Q

n for crown glass

A

1.523

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5
Q

Saddle

A

bridge type that is curvy on top and bottom, does not protrude

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6
Q

Describe ophthalmic crown glass transmission characteristics

A

10% reflection, not a good UV blocker

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7
Q

uncorrected axial myope or hyperope has larger image size?

A

myope has larger image size

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8
Q

What is the total spectical magnification equation?

A

Shape factor * power factor

( 1 / (1-[t/n]F1) ) * (1 / (1-hFv)

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9
Q

___% of lenses are AR coated in the US

A

30

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10
Q

What are the specific gravities?

A

Crown glass specific gravity 2.54

CR-39 SG 1.32

Polycarbonate SG 1.20

Trivex SG 1.11

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11
Q

CR-39 specific gravity:

A

1.32

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12
Q

What is a mounting? What are the 3 brands?

A

The “frame” for rimless or semirimless glasses

Balgrip/Ilford

Numont

Wils-Edge

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13
Q

What is the “rule of thumb” for aniseikonia?

A

1.00D difference between eyes has 1% image size difference

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14
Q

What is the Abbey for crown glass?

A

59

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15
Q

What is the UV spectrum

A

200-380 nm

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16
Q

According to Knapp’s law, how are axial myopes best treated? Refractive myopes? what does correcting in these ways help avoid?

A

axial best treated with spectacles (but CLs are ok too, clinically)

refractive with CLs

these help avoid Aniseikonia

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17
Q

Index of coating equation:

A

nc= sqrt (nL)

nc = index of coating needed

nL = index of lens

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18
Q

What is Malus’ law of polarization?

A

I0 = Icos2 θ​

I = initial light intensity

I0 = new light intensity

theta = angle between transmission axis of the 2 polarizers

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19
Q

Which hinge type has the “shield” visible from the font?

A

Riveted hinge

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20
Q

What is Knapp’s Law?

A

axial ametropic eyes corrected with specs will have similar retinal sizes as an emetropic eye.

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21
Q

Which metal frames are hypoallergenic?

A

Titanium, flexon, stainless steel

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22
Q

Semisaddle

A

Bridge protrudes a little in front and has plastic nose pads

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23
Q

Stainless steel characteristics, pros/cons

A

steel chromium alloy

hypoallergenic yes
lightweight yes
strong yes
flexible no, springy
corrosion-resistant yes

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24
Q

What is invovled in Vertical alighment of frames (step 2)

A

4 point touch test (lenses and nose are all in same plane), make sure there is no X-ing

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25
Neutralization in AR happens when the path difference is an ___ number of half wavelengths
odd
26
Distracting glare is...
caused by annoying lens reflections. AR can help
27
Flexon characteristics, pros/cons
Titanium alloy (Marchon), AKA memory metal hypoallergenic yes lightweight yes strong yes flexible highly flexible can bend to original shape corrosion resistant yes hard to adjust, patterns not as available
28
Crown glass specific gravity
2.54
29
Most AR coatings are ___ layers
Most AR coatings are **5-6 or as many as 11** layers
30
Which material is extremly heat and solvent sensitive and is very lightweight and hypoallergenic?
Propionate
31
Beryllium, characteristics, pros/cons
low-cost alternative to titanium hypoallergenic **no** lightweight yes strong yes flexible yes, but springy corrosion resistant yes good for salty/acidic patients
32
What is "In-mass" photochromics?
spiropyran photochromics throughout the lens
33
Which nosepad is flexible, slippery?
Vinyl
34
What are the different temple styles?
skull library convertible (either of 1st two depending on how bent) riding bow (curve in plastic) comfort cable (curve in metal)
35
Which temple is curved in plastic?
riding bow
36
What is the equation for changing spec RX into CL RX?
Fs / (1 - dFs)
37
What wavelength is generally selected for AR?
want to block 555 nm
38
How does astigmatism affect spec mag? What about in CLs?
each diopter of cyl makes a difference in mag by 1.5% 0.3% for CLs
39
Polycarbonate specific gravity:
1.20
40
Reflected glare is...
caused by reflected light. AKA blinding glare
41
1.10 would be \_\_\_% magnification, 0.92 would be \_\_\_% minification
10% and 8%
42
What is the Abbey for CR-39?
58
43
What are some problems you can have by correcting refractive error of anisometropia?
Magnification differences, vertical imbalance when reading, and horizontal vergence problems
44
what are the two types of mirror coatings?
metalic (scratches easily) and dielectric (durable)
45
What is essential for calculating Lambert's law of absorption?
the trasmittance factor (q)
46
Discomfort glare is....
in field of view but does not interfere with resolution
47
The best AR should have a thickness \_\_\_% of the desired wavelength
The best AR should have a thickness **25**% of the desired wavelength
48
What is the outermost layer of AR?
**hydrophobic** coating that also increases hardness to prevent scratching
49
How is AR applied to plastic?
clean, bake to remove water, 100 deg C heating in vaccum, quartz for outer layer.
50
If there is too much vertical imbalance for reading because of anisometropia, what lens technique can fix the vertical imballance?
**Slab off** removes base down from the most minus lens
51
How is AR applied to glass?
cleaning, heated in vaccum, AR heated even higher
52
n for polycarbonate
1.586
53
Aluminum characteristics, pros/cons
hypoallergenic no lightweight yes strong yes flexible no corrosion resistant yes good to very good resistance, high luster, light lens often have "gapping", complicated manufacturing with rivets
54
What is imbibed photocrhomic technology?
spiropyrans are in a surface coating for consistant darkening
55
What is ultimate transmission?
multiplying the seperate transmition of each lens to find ultimate transmission
56
symmetrical vs asymmetrical aniseikonia:
**Symmetrical**: size change is equal in all directions **Asymmetrical: meridonial** image size is changed in one dimention (not both) or there is disortion (progressive changes in dimmensions)
57
Anisometropia vs aniseikonia?
Anisometropia : unequal refractive error aniseikonia: differing retinal image sizes
58
What is the W bridge?
it's the metal saddle (has no nose pieces)
59
Which nosepad is hard and nonflexible?
Acetate
60
Titanium characteristics, pros/cons
hypoallergenic yes lightweight yes strong yes flexible **no** corrosion resistant yes very light and hard, hypoallergenic very expensive, not very flexible
61
Image size differences greater than \_\_\_\_% will usually result in loss of binocularity
Image size differences greater than **5%** will usually result in **loss of binocularity**
62
Zyl characterisics, pros/cons
hypoallergenic yes lightweight yes strong no flexible no colors, easily worked, can grow/shrink for sizing errors Brittle with age, lose luster, heavier than other plastic frames
63
If a patient's reading position is 10 mm below optical centers, how much anisometropia can they have before they will have symptomatic vertical imballance?
1.00D of aniso. This means that the person experiences 1 prism D of vertical imballance.
64
Which temple is curved in metal?
comfort cable
65
What is the Abbey for Trivex?
43-46
66
Describe polycarbonate transmission characteristics
10% reflection, great UV blocker
67
Optical density equation:
OD = -log(Transmission)
68
n for Crown glass CR-39 Polycarbonate Trivex
Crown glass N=1.523 CR-39 N= 1.499 Polycarbonate N=1.586 Trivex N=1.53
69
n for trivex
1.53
70
What are the steps to get frames into standard alignment?
1. Horizontal alignment, 2 Vertical alignmnet (4 point touch test) 3: Open Temple Alignment (90-95 deg) 4: Temple Parallelism (flat surface touch test upsidedown) 5: Alignment of the bent-down portion of the temple (rightside up) 6: Temple-fold angle
71
Which metal frames are flexible?
Monel, (Flexon), Beryllium (springy)
72
low refractive error (probably less than +/-4.00D) is refractive or axial?
low refractive error is a combination of both refractive and axial!
73
How are mirrored coatings accomplished?
constructive interference on front of lens
74
Propianate characteristics, pros/cons
hypoallergenic yes very hypoallergenic lightweight yes very hypoallergenic strong no flexible yes less "dulling" food flex, very **lightweight and hypoallergenic** **not as common a zyl, heat and solvent sensitive**. lens size has to be exact
75
What is the reflection equation?
Note that it's like n2-n1 front surface: (1.5-1) back surface (1-1.5) i is intensity
76
What is a modified saddle?
the semisaddle (has plastic nose piece).
77
What are the abbey numbers?
Crown glass Abbey 59 CR-39 Abbey 58 Polycarbonate Abbey 30 Trivex Abbey 43-46
78
polarized lenses removes.... How is the transmission axis ortiented?
specularly reflected horizontally polarized light. the transmissiona axis is at 90 degrees
79
Describe CR-39 transmission characteristics
10% reflection, improved UV blocker
80
What is asthenopia?
eyestrain from dissimilar images. eyes feel "funny", HA, photophobia, nerviousness. ## Footnote **occluding an eye relieves these symptoms**
81
Trivex specific gravity
1.11
82
What is aniseikonia?
unequal **image retinal size** or unequal shape differences between retinal images
83
uncorrected **refractive** myope or hyperope has larger image size?
neither! it's about the same
84
Which nosepad is grippy and sticky?
Silicone
85
What is the power factor equation?
( 1 / (1-hFv)
86
What is the visible spectrum?
380-760 nm
87
Which hinge has apperatus anchored directly into plastic?
Hidden hinge
88
Brewster's angle equation
Tan i = n. i is the angle between ray and the normal
89
comfort bridge
has ugly nose piece
90
Disability glare is....
causes **lower contrast,** does interfere with resolution. Central 10 degrees of visual field. Prevent with deeper tints or photochromics
91
Reinformcement in AR happens when the path difference is an ___ number of half wavelengths
even
92
Monel characteristics, pros/cons
most widely used, has nickel (and copper, etc) hypoallergenic no lightweight no strong no flexible highly flexible corrosion resistant yes (when plated) Cost-effective and efficient, malleable medium corrosion resistance unless plated, heavier
93
A high Rx greater than \_\_\_D is usually from abnormal axial legnth
+/- 4.00 D
94
n for Cr-39
1.499
95
Ultimate opacity equation:
O\*O\*O or (1/T)(1/T)
96
how long does AR take to apply?
4 to 10 hours
97
Which frame material is thermoelastic?
Optyl
98
What are the different endpiece types? 6
American, English, French, butt-type, mitre-type, turn-back
99
Anisometropia is....
when the Seq of both eyes differ by 1.00 D or more
100
Opacity equation:
O= 1/Transmission
101
Keyhole
A bridge type (the nose is the "key")
102
Optyl characteristics, pros/cons
Thermo**elastic** hypoallergenic yes lightweight yes strong yes flexible yes very light, excellent shape retetion, hypo-allergenic, very heat and solvent resistant Difficult adjustments that require heat, will not shrink
103
What is the shape factor equation?
1 / (1- [t/n] F1)
104
What is the most popular plastic frames material?
Zyl, or cellulose acetate

Ophthalmic optics 2 (4 decks)

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