Exam 1 Flashcards

Question

Trivex specific gravity

Answer 1

OD = -log(Transmission)

Answer 2

caused by annoying lens reflections. AR can help

Answer 3

in field of view but does not interfere with resolution

Answer 4

causes **lower contrast,** does interfere with resolution. Central 10 degrees of visual field. Prevent with deeper tints or photochromics

Answer 5

caused by reflected light. AKA blinding glare

Answer 6

specularly reflected horizontally polarized light. the transmissiona axis is at 90 degrees

Answer 7

Tan i = n. i is the angle between ray and the normal

Answer 8

I₀ = Icos² θ I = initial light intensity I_{0 = new light intensity} _{theta = angle between transmission axis of the 2 polarizers}

Answer 9

spiropyran photochromics throughout the lens

Answer 10

spiropyrans are in a surface coating for consistant darkening

Answer 11

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

Answer 12

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

Answer 13

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

Answer 14

n_c= sqrt (n_L) nc = index of coating needed nL = index of lens

Answer 15

The best AR should have a thickness **25**% of the desired wavelength

Answer 16

want to block 555 nm

Answer 17

cleaning, heated in vaccum, AR heated even higher

Answer 18

clean, bake to remove water, 100 deg C heating in vaccum, quartz for outer layer.

Answer 19

4 to 10 hours

Answer 20

**hydrophobic** coating that also increases hardness to prevent scratching

Answer 21

Most AR coatings are **5-6 or as many as 11** layers

Answer 22

constructive interference on front of lens

Answer 23

metalic (scratches easily) and dielectric (durable)

Answer 24

The "frame" for rimless or semirimless glasses Balgrip/Ilford Numont Wils-Edge

Answer 25

A bridge type (the nose is the "key")

Answer 26

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

Answer 27

has ugly nose piece

Answer 28

Bridge protrudes a little in front and has plastic nose pads

Answer 29

the semisaddle (has plastic nose piece).

Answer 30

it's the metal saddle (has no nose pieces)

Answer 31

American, English, French, butt-type, mitre-type, turn-back

Answer 32

Riveted hinge

Answer 33

Hidden hinge

Answer 34

skull library convertible (either of 1st two depending on how bent) riding bow (curve in plastic) comfort cable (curve in metal)

Answer 35

riding bow

Answer 36

comfort cable

Answer 37

Magnification differences, vertical imbalance when reading, and horizontal vergence problems

Answer 38

when the Seq of both eyes differ by 1.00 D or more

Answer 39

Anisometropia : unequal refractive error aniseikonia: differing retinal image sizes

Answer 40

1.00D of aniso. This means that the person experiences 1 prism D of vertical imballance.

Answer 41

**Slab off** removes base down from the most minus lens

Answer 42

unequal **image retinal size** or unequal shape differences between retinal images

Answer 43

**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)

Answer 44

eyestrain from dissimilar images. eyes feel "funny", HA, photophobia, nerviousness. ## Footnote **occluding an eye relieves these symptoms**

Answer 45

10% and 8%

Answer 46

Shape factor \* power factor | ( 1 / (1-[t/n]F₁) ) \* (1 / (1-hF_v)

Answer 47

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

Answer 48

( 1 / (1-hFv)

Answer 49

Fs / (1 - dFs)

Answer 50

each diopter of cyl makes a difference in mag by 1.5% 0.3% for CLs

Answer 51

myope has larger image size

Answer 52

neither! it's about the same

Answer 53

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

Answer 54

axial best treated with spectacles (but CLs are ok too, clinically) refractive with CLs these help avoid Aniseikonia

Answer 55

+/- 4.00 D

Answer 56

low refractive error is a combination of both refractive and axial!

Answer 57

Image size differences greater than **5%** will usually result in **loss of binocularity**

Answer 58

1.00D difference between eyes has 1% image size difference

Answer 59

Zyl, or cellulose acetate

Answer 60

hypoallergenic yes lightweight yes strong no flexible no

Answer 61

colors, easily worked, can grow/shrink for sizing errors Brittle with age, lose luster, heavier than other plastic frames

Answer 62

hypoallergenic yes very hypoallergenic lightweight yes very hypoallergenic strong no flexible yes

Answer 63

less "dulling" food flex, very **lightweight and hypoallergenic** **not as common a zyl**, **heat and solvent sensitive****.** lens size has to be exact

Answer 64

Thermo**elastic** hypoallergenic yes lightweight yes strong yes flexible yes

Answer 65

very light, excellent shape retetion, hypo-allergenic, very heat and solvent resistant Difficult adjustments that require heat, will not shrink

Answer 66

hypoallergenic no lightweight yes strong yes flexible no corrosion resistant **yes**

Answer 67

good to very good resistance, high luster, light lens often have "gapping", complicated manufacturing with rivets

Answer 68

most widely used, has nickel (and copper, etc) hypoallergenic **no** lightweight no strong no flexible highly flexible corrosion resistant yes (when plated)

Answer 69

Cost-effective and efficient, malleable medium corrosion resistance unless plated, heavier

Answer 70

hypoallergenic yes lightweight yes strong yes flexible **no** corrosion resistant yes

Answer 71

very light and hard, hypoallergenic very expensive, not very flexible

Answer 72

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

Answer 73

low-cost alternative to titanium hypoallergenic **no** lightweight yes strong yes flexible yes, but springy corrosion resistant yes good for salty/acidic patients

Answer 74

steel chromium alloy hypoallergenic yes lightweight yes strong yes flexible **no, springy** corrosion-resistant yes