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Ophthalmic Optics Block 11 > Environmental Applications > Flashcards

Environmental Applications Flashcards

1
Q

High mass impact for lenses

A

Drop ball test

Steel ball dropped from 50inches

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2
Q

High velocity impact

A

Pointed projective, fired at 150ft/sec

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3
Q

What are the two tests used to verify resistance

A

High mass impact (drop ball test)

High velocity impact

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4
Q

Glasses designed to be impact resistance: heat treatment

A

Tempering or toughening glass lenses, lenses are a heated to about 700C for 2-3 minutes and then cooled rapidly with both surfaces fannaed simultaneouslt
-the outside of the lens will cool first and shrink, thereby pulling inward on the outer layers. This creates tension or stress and result in outer protective shell and 2-3 times greater impact resistance

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5
Q

Making glass impact resistance: chemical treatment

A

Chemical tempering, the process of increasing the impact of resistance of glass lenses by immersing them in a bath of molten potassium nitrate
-this induces an exchange of the sodium ions in the glass surface with the 30% larger potassium ions. The result in a more tightly packed surface layer that creates a layer of tension

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6
Q

______ treatment of glass results in greater impact resistance

A

Chemical

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7
Q

_____ treatment of glass can be applied to objects of complex shape

A

Chemical

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8
Q

_____ treatment of glass is quick

A

Heat

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9
Q

_____ treatment equipment for glass is inexpensive

A

Heat

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10
Q

How is glass tempering verified

A

Polariscope

  • consists of two polarized filters, one on the top and one on the bottom of the instrument with their absorption are perpendicular (cross polarized)
  • a normal lenses placed between the Dolores appears uniformly dark
  • a tempered lens will demonstrate stress partners: Maltese cross
  • polariscopes rarely found in practice CEO’s
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11
Q

Specification of occupational safety lenses

A

Minimum coverage area

Markings

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12
Q

787+

A

Impact rated Plano

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13
Q

Z87-2+

A

Impact rated Rx

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14
Q

V in occupational safety glasses

A

Variable tint

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15
Q

Lens type: W and shade number

A

Welding

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16
Q

Lense type: UV filter

A

U and scale number

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17
Q

Lens type: visible light filter

A

L and scale number

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18
Q

Non-impact lenses

A

Z87

Z87-2

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19
Q

Enchroma lenses

A

Color deficiency

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20
Q

Oxy-Iso glasses

A
  • aimed at those with color deficiency or those working with veins and blood (nurses and phlebotomist)
  • enhances the O2 signal from hemoglobin under the skin, amplifies the perception of veins under the skin
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21
Q

Switch vision in space

A
  • two frames passed NASAs rigorous testing and will be worn by astronauts
  • supplies the interchangeable magnetic prescription lenses
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22
Q

3D printing and frame design

A

Companies can 3D print their frames now

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23
Q

Close caption classes

A

For movie theaters

Have the closed caption inside the lenses

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24
Q

Stick on bifocals

A

Put them where they want

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25
Q

Snap spectacles

A

Smart glasses
Recording as you go
Snapchat
Social media

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26
Q

Conduction technology and glasses

A

Bone conduction tech so you dont need earphones, controls music and calls

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27
Q

Smart glasses

A
  • liquid lenses change shape according to the distance of objects
  • lenses made of glycerin inflexible membranes that’s move back and forth to change the curvature of the lens
  • distance in meter on the bridge
  • takes about 14 miliscedonds to change Rx
28
Q

Oakley smart glasses

A

Snowboarding/skiing glasses

  • connect to internet
  • play music
  • show routes and elevation
  • show speed
29
Q

Solution to reflection with anti-reflective coating:p ath condition

A

Where the AR coating applied to the lens surface is 1/4 of the wavelength of light thick, the reflected path from the back fo the coating will be a 1/2 wavenlerght longer. Light reflected form the back of the coating is this 180 degrees out of phase from light reflected from the front. If the amplitude of light reflected at each surface of the coating is equal when they will cancel each other out

30
Q

Amplitude condition for AR coating

A

Where the amplitude of light reflected from each surface of an AR coating is equal and, if 180 degrees out of phase, will cancel each other out. For this to occur, the refractive index of the coating must equal to the square root of the refractive index of the lens material

N(coating)=square root of n(lens)

31
Q

If it is _____ out of phase, in antifrelfective coating, it will cancel each other out

A

180 degrees

32
Q

Why do the multiple layers on anti reflective coating have different refractive indices

A

More wavelength specific

33
Q

Corning

A

Original company that makes glass lenses and photochromics

34
Q

Original glass photochromic manufacturers

A 
Corning photochtomic 
1.60-1.90
Very high quality 
Decades of normal use
Reactions mediated by atoms of silver
35
Q

Drive safe lenses by ZEISS

A

Designed to reduce glare while driving at night
Designed to maintain an accurate view of the road, dashboard, near and side view mirrors
Luminance design technology
-changes in the size of the drivers pupils is taken into account while driving

36
Q

Short fit progressive

A

Short corridor

  • ransitions quicker
  • fits in a smaller frame
  • B m,easurements of less than 30 is smaller
37
Q

Occupational progressive

A
  • lens designed to emphasize intermediate and near vision
  • computer use, office work
  • very wide inter, near-low leave of unwanted astigmatism in periphery. Widens corridor because less change in add power is required over a longer distance
38
Q

Double segment flattop bifocals (double D)

A

-bottom-near
-top-near
-remainder-distance
0for people who work in confined spaces that need to see up close, above and below them, without moving their heads

39
Q

DD occupational lens (tri)

A

Bottom-near
Top-intermediate or near
Remainder-distance

40
Q

Electricians, mechanics, painters need what kind of lenses

A

Double segment flat top bifocals (double D)

41
Q

Balance lenses

A

Lens placed in a frame which looks like the lens for the opposite eye to balance appearance and weight
-balance/bal on Rx indicates the designated eye is not sighted, so the same number should be entered for both eyes

42
Q

Bi-convex lenses

A

A lens style where both the front and back surfaces are plus

43
Q

Bi-concave

A

A lens style where both front and back surfaces are minus

44
Q

Distance only correction in one eye, near vision correction in the other eye- results in acceptable clear vision at both distances

A

Monovision

45
Q

Eye that sees distance in monovision

A

Will be blurred up close and the yees that sees near will be blurred at distance

46
Q

Which eye is usually used for distance vision in monovision

A

Dominant

47
Q

Why is the term monovision misleading

A

The two eyes still work together to see clearly, but one eye sees more clearly than the other at each distance

48
Q

Limitations of monovision

A
  • distant objects appear slightly blurred
  • lack intermediate vision
  • doesn’t provide adequate near vision for sustained reading
  • although the two euyes are still working together, binocular vision is compromised, causeing a decrease in depth perception
49
Q

Generally used to correct extreme hyperopia. Designed to limit the thickness and weight that a high powered lens would normally required, all of the power of the lens is concentrated in a small area in the center

A

Lenticular lens

50
Q

Minus lenticular lens

A

Myodisc

51
Q

Techniques to reduce thickness: frame shape and seize

A
  • smaller lens opening
  • less wide, less tall, rounder the better
  • plus Rx: smaller a good idea but less impact than minus RX
52
Q

Techniques to reduce thickness: frame type

A
  • avoid rimless and semi-rimless frames

- full plastic frames hide thickness

53
Q

Techniques to reduce thickness

A 
Frame shape and size 
Frame type 
Lens edging choices to hide thickness 
Hi index lenses 
Roll and polish 
Centering the OC over the GC
Edge painting-edge matched to frame color
54
Q

Rolling and polishing to reduce thickness: pros

A

Exposed edges are polished to enhance finished, “invisible” look of lens

55
Q

Cons of rolling and polishing to reduce thickness

A

Seeing rainbows around edges

56
Q

Adaptation issues: base curve

A
  • flatter BC result in thinner lense,s steeper BC have less distortion
  • pts should adapt to small BC changes within a week
  • happens with patients sensitive to subtle changes in vision, when patient gets a second pair of similar eyewear, or when the patient only replaces one lens
  • when possible, keep the BC similar/same between the two eyes and similar/same as previous BC
57
Q

Giving roll and polishing to patients

A

Must talk to patients about it. Some patients hate it

58
Q

Polycarb adaptation issues

A

Low abbe number: complaints about VA and chromatic aberration
-visual distortion of colors

59
Q

Adaptation issues with polarization

A

Some people have issues with it

60
Q

Most common adaptation issues

A

Base curve
Polycarbonate
Polarization

61
Q

Potentially the first example of sunaglasses

A

1790

62
Q

D-specs

A

For light sensitivity

Maybe to hide a defamation

63
Q

Edward Scarlett

A

1727

Worlds oldest pair of specs with sides

64
Q

Worlds oldest pair of specs with sides

A

Edward Scarlett in 1727

65
Q

First known mass production of eyewear

A

Turn around time was 18 months

Not sure of the time

66
Q

Eyewear in culture

A

1951

  • marketing multiple types of glasses to women
  • not about Rx, about looks
67
Q

Why does bono wear sunglasses

A

He has glaucoma and has light sensitivity

Ophthalmic Optics Block 11 (4 decks)

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