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OPT 2461L Ophthalmic Dispensing Lab 2 > UNIT 3: Tints, Coatings, and Special Lens Designs > Flashcards

UNIT 3: Tints, Coatings, and Special Lens Designs Flashcards

1
Q

Electromagnetic Radiation

A
  • Ultraviolet:
    1) UVC: 200 - 275 nm Ozone Layer
    2) UVB: 275 - 330 nm Sunburn
    3) UVA: 330 - 400 nm Ocular Hazard
  • Visible Light:
    1) 400 - 750 nm ROYGBIV
  • Infrared Heat
    1) 750 - 1,000,000 nm
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2
Q

Light

A
  • Light deviates from a source in waves
  • Speed of light in air = 186,000 miles per
    second.
  • Light striking a different medium is
    reflected ( 4% from each lens surface ),
    refracted or absorbed.
  • Speed of light in air divided by the speed of
    light in medium = index of refraction.
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3
Q

The Metric System

A

1 meter = 39.37 inches
1 meter = 10 decimeters
1 meter = 100 centimeters
1 meter = 1000 millimeters
1 meter = 1 billion nanometer ( nm )

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4
Q

Lens Material Characteristics

A
  • Index of refraction
  • Abbe Value
  • Specific Gravity
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5
Q

Index of refraction

A

When light strikes a new medium at an angle, the change in speed causes it to change direction. The higher the index, the greater the change.

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6
Q

Abbe Value

A

The higher the value , the less chromatic aberration present in a lens.

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7
Q

Specific Gravity

A

The ratio of the weight of a substance to the weight of water with the same volume. The lower the number, the lighter the lens.

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8
Q

Crown

A

Index: 1.52
Specific Gravity: 2.54
ABBE: 59

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9
Q

CR-39

A

Index: 1.498
Specific Gravity: 1.32
ABBE: 58

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10
Q

Spectralite

A

Index: 1.54
Specific Gravity: 1.21
ABBE: 47

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11
Q

Trivex

A

Index: 1.53
Specific Gravity: 1.11
ABBE: 45

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12
Q

Thin & Lite

A

Index: 1.60
Specific Gravity: 1.34
ABBE: 36

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13
Q

Polycarbonate

A

Index: 1.59
Specific Gravity: 1.20
ABBE: 31

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14
Q

Glass

A

Index: 1.70
Specific Gravity: 2.99
ABBE: 32

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15
Q

Tints and Coatings

A
  • UV
  • Tints
  • Photosensitive or Variable tint
  • AR Coating
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16
Q

UV Coating

A

Block UV light to 400nm

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17
Q

Tints

A
  • Glass: Metal oxides added for color
  • Plastic: Lenses dyed to color
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18
Q

Photosensitive or Variable Tint

A
  • UV darkens
  • IR lightens
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19
Q

AR Coating

A
  • 1/4 wave length thick
  • Material equal to square root of lens (
    magnesium fluoride )
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20
Q

Tints

A
  • Gray: Neutral, balanced color
  • Brown: Reduces blue increases contrast
  • Green: Reduces blue and red
  • Yellow: Enhanced contrast
  • Pink: Reduces blue
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21
Q

Polarized lenses

A
  • Stretched sheet of polyvinyl acetate dipped
    in iodine only allows vertically vibrating
    light waves to pass through.
  • Film dyed to desired color
  • Laminated or embedded
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22
Q

What are the advantages of polarized sunglasses?

A
  • Decrease driving fatigue
  • Water sports
  • Snow
  • True colors
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23
Q

Younger Optics NuPolar

A
  • The lens has a 99% polarizing efficiency, blocks virtually all glare, and enhances contrast for maximum visual clarity.
  • Image wrap: +8.25D Base curve decentered
    PAL polycarbonate with NuPolar.
  • New 1.67 Index
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24
Q

Essilor Xperio Polarized

A
  • Polarized lenses from Essilor, KBco and
    Specialty Lens Corp.
  • 37 Unique Lens design and material
    combinations.
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25
Q

Specialty Lens Corp

A
  • New progressive design under the iRx
    polarized brand, available in CR- 39,
    Polycarbonate, 1.56, 1.60, & 1.67 index
    options.
  • Designed by Essilor
  • Smoke, Chocolate, Ash, Carmel, Forest,
    Copper, Ruby, Sunflower, Violet, Sunset,
    Rose, Ocean & Grass.
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26
Q

KBco

A
  • Wrap Solutions polarized
  • +8.25 B.C. Aspherically compensated
  • No special surfacing equipment required
  • Available in polycarbonate single vision and
    EOS wrap progressive.
  • True Grey, Grey - C & Brown - C
  • Kbco.net
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27
Q

Vision - Ease : Coppertone

A
  • The polarized technology eliminates
    reflected glare and delivers super UV and
    blue light protection to help the wearer
    avoid cataracts, macular degeneration, and
    premature wrinkles around the eyes.
  • Polycarbonate grey or brown
  • SV, FT, & PAL’s
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28
Q

Wiley X: Fishing & Boating

A
  • Wiley X is one of the few companies that
    can prescribe frames with 8 base
    curvatures. Now flat prescription frames
    are a thing of the past.
  • Uses only shatterproof polycarbonate
    which is the most impact resistant lens
    material available.
  • Patients can locate the nearest Wiley X
    dealer with the Wiley X Dealer locator.
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29
Q

Costa Del Mar

A
  • 580 Lenses:
    • Polarized glass
    • Blue, Green & Silver Mirror, Gray, Copper
  • 400 Lenses
    • Polarized glass, CR-39 & polycarbonate
    • Blue & green, gray, amber, vermillion,
      sunrise.
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30
Q

Kaenon Polarized

A
  • Same purpose-built lens tints and light
    transmission-level lens innovations that
    are available in non-prescription Kaenon
    polarized lenses.
  • SR-91 polarized lenses 1.56 Index 1.15
    Specific Gravity 40 abbe.
  • Anti - reflective treatment applied to front
    and rear of RX lens.
  • All Kaenon polarized frame styles are RX -
    friendly, including KORE and the variant
    series.
  • Kore, Variant series and Basis RX lenses
    receive front - side flash mirror treatment
    and laser engraved logo on front, anti -
    reflective treatment applied to rear - side.
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31
Q

Rudy Project

A
  • RX direct in frame interchangeable system
  • Rx their favorite Rudy models directly in the
    frame.
  • 2 or 3 RX lenses in different tints to manage
    any light condition. Lenses interchange in a
    snap, yet stay snugly in place during
    sports.
  • S. V progressive
  • Clear, transitions, KBco wraps
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32
Q

Photochromism

A
  • Greek:
    • Phos = light
    • Chroma = color
  • Defines a light - induced, reversible color
    change activated by EM radiation.
  • Discovered late 1880’s
  • Can occur in organic or inorganic materials
  • Involves a reversible chemical reaction:
    • Colorless molecules converted to colored
      form that’s reversible.
    • Activated by UV light
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33
Q

Photochromic Lens History Time Line

A
  • 1940’s: Corning Glass begins experimenting
  • 1962: Corning Photo Gray glass lenses
    released
  • 1960’s and 1970’s: an array of glass
    photochromic lenses
  • 1974: Fusible photochromic glass
    segmented multifocals
    • Flat tops and round segments
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34
Q

Glass Photochromic Lenses

A
  • Silver halide crystals
  • Performance factors:
    • Light intensity
    • Temperature
    • Lens thickness
    • Hardening
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35
Q

What year did PPG discover a new family of photochromic compounds - blue pyridobenoxazines?

A

1983

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36
Q

When did PPG & Essilor partner to form Transitions Optical Inc?

A

1990

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37
Q

When did Transitions Plus launch?

A

1992

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38
Q

When did Transitions 3 come out?

A

1996

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39
Q

When did Transitions Next Generation come out?

A

2002

40
Q

When did Transitions V lenses come out?

A

2005

41
Q

2008 Transitions VI & 2014 Transitions VII

A
  • Enhanced photochromic performance
    across all major lens materials and
    designs.
  • Gets clearer and becomes darker and does
    both faster.
  • Better performance in warm climates.
  • UV protection extended to the 400nm level.
42
Q

Photochromism

A

A light induced reversible change in color

43
Q

Factors affecting lens performance

A

UV radiation and Temperature

44
Q

Photochromic Lens Manufacturing Processes

A
  • First photochromics were Crown glass
  • Photochromic materials are added to the
    lens material.
  • Glass lenses use silver halide crystals
45
Q

Corning SunSensor

A
  • Distributes photochromic molecules
    throughout the lens, allowing a consistent
    and effective light response for the life of
    the lens.
  • Available in single vision and progressive
    lens designs.
  • 1.56 Index Grey or Brown
46
Q

Rodenstock

A
  • In mass photochromic material distributes
    photochromic molecules throughout the
    lens, allowing a consistent and effective
    light response for the life of the lens.
  • 1.52 plastic ColorMatic Extra SV, BF, and
    PAL grey or brown.
  • Darkens up to 50% in the car
47
Q

Plastic Photochromic Film Lenses

A
  • Vision Ease LifeRX Photochromic
  • Photochromic impregnated film is
    positioned between two thin wafers of
    polycarbonate.
  • Available in grey, brown, SV, FT, and PAL
48
Q

Making Plastic Photochromic Lenses

A
  • Use a photochromic impregnated film
    inside the lens.
49
Q

Photochromic Coating

A
  • Photochromic molecules added to a carrier
    medium and coated onto the lens surface.
  • Corning Sun Sensors HPC
  • Made by Polycore Optical USA
  • 1.60 & Polcarbonate
  • Fast Reacting
50
Q

Matrix Bonding

A
  • 0.8mm photochromic matrix layer bonded
    to front surface of the lens and covered
    with an anti- scratch coating.
  • To avoid damage during surfacing, the lab
    must adhere to minimum center and edge
    thicknesses.
51
Q

Kodak Instashades

A
  • The rapid reaction photochromic matrix is
    chemically interlocked to the lens substrate
    to ensure KODAK InstaShades Lenses have
    a long life.
52
Q

Imbibition

A
  • Photochromic compounds driven 0.15mm
    into the front surface.
  • Molecules become permanently molded
    into the surface and part of the lens.
  • Cannot scratch or peel off
53
Q

Transbonding

A
  • Some material are not ideal photochromic
    substrates.
  • Applies proprietary surface treatments in a
    series of layers.
  • Help apply transitions photochromic
    technology to lens materials previously
    considered unsuitable.
54
Q

Transitions Lenses

A
  • Block 100% UVA and UVB
  • Provide UV 400 protection
  • Compatible with all major AR treatments
  • With AR treatment, they are even clearer
    than hard coated lenses.
  • Available in the most popular materials and
    designs.
55
Q

Transitions Xtra Active

A
  • Darker outdoors in normal and hot temps
  • Slight tint indoors
  • Activate moderately behind the windshield
  • Block 100% UVA and UVB
  • Gray activates to green gray color
  • Poly, Trivex, & 1.67
56
Q

Transitions Drivewear

A
  • Responds to visible and UV light
  • Provide glare protection through
    polarization.
  • Control light under varying outdoor lighting
    condition.
57
Q

Corning CPF Lenses

A
  • CPF 450: Albinism, Psedophakia
  • CPF 511: Macular Degeneration, Cataracts
  • CPF 527: Diabetic Retinopathy
  • CPF 550: Retinitis Pigmentosa
  • CPF 550XD: Achromatism
58
Q

Fundamental of Light

A
  • Light is created by radiant sources and
    emitted in waves.
  • Light travels from its source in wavefronts.
59
Q

Antireflective Coating

A
  • Path equals thickness, 1/4 wavelength or
    odd multiples.
  • Amplitude equals top to bottom of wave,
    Index of the film must equal square root of
    lens material index.
  • Materials: Magnesium Fluoride, titanium,
    zirconium, sodium dioxide
  • Hydrophobic coating
60
Q

The EM Spectrum

A
  • Light is part of the EM spectrum
  • Creates magnet field around the wave
  • Wavelengths from extremely long to
    extremely short.
  • Visible region = a tiny sliver ( 380nm -
    760nm)
  • UV above visible; infrared below this ( both
    are invisible)
61
Q

Wavelengths and Colors

A

As the eye receives one wavelength or a small grouping of wavelengths, it sees a single color.

62
Q

Anatomy of a Wave

A
  • Amplitude:
    Maxima and Minima
  • Wavelength
  • 0-360 = 1 Wavelength or cycle
63
Q

Law of Reflection

A

Angle of incidence = angle of reflection

64
Q

Reflections and Lenses

A
  • Towards observer
  • Towards wearer
65
Q

What can AR reduce?

A
  • Eyestrain
  • Eye Fatigue
  • Headaches
  • Loss of focus
66
Q

What percent of computer users suffer from eye strain?

A

88%

67
Q

What percent preferred AR lenses compared to hard coated lenses?

A

86%

68
Q

What percentage preferred AR lenses for computer use?

A

62%

69
Q

What percent preferred AR lenses for night driving?

A

69.6%

70
Q

What percent chose AR lenses for visual comfort?

A

59.8%

71
Q

What percent AR lenses for reduction of reflections?

A

71.7%

72
Q

What percent of wearers would purchase AR again?

A

98%

73
Q

Antireflective System

A
  • Combo scratch coat and 9-layer AR
    coating per side:
    -Include 3 quartz-like layers
    -Green, Gold, Purple color
    -Hydrophobic layer
  • ~1% reflection per surface
74
Q

How long do AR lenses last?

A

2 years

75
Q

How scratch resistant is the coating?

A
  • Automated repeatable abrasion test
    using Colts Laboratory’s Scratch
    Testing Device.
  • Steel wool pad rubbed against
    convex side of lens under 5 pound
    weight for 200 cycles.
76
Q

Abrasion Resistant Coatings

A
  • Inorganic: Evaporating a material
    like quartz in a vacuum chamber.
  • Organic: Chemical mixtures bonded
    with lens surface.
77
Q

List the different abrasion resistant coatings tests

A
  • Bayer Test:
    Lens placed in Pan with sand and
    moved back and forth.
  • Tabor Test:
    Lens placed on turntable, exposed
    to 2 abrasive wheels.
  • Steel Wool Test:
    Steel wool pad attached to arm,
    moved across lens surfaces for
    standard time and pressure.
  • Tumble Test:
    Tumbles in barrel filled with
    abrasive material - supposed to be
    equivalent to one years wear.
78
Q

Three main uses for aspheric curves

A
  • Optical aberration control:
    Improved off center optics for RX’s
    > +7.00 or -23.00D than spherical
    base curve.
  • Cosmetic:
    Allows the use of flatter base curves
    while maintaining good optics.
  • Power change:
    Used for progressive addition
    lenses.
79
Q

Tscherning Ellipse

A
  • A graphical representation of the
    front surface power as a function of
    the total lens power in best form
    lenses.
  • There are two possible solutions,
    those that are least curved and
    those that are most curved.
80
Q

What is the least curved portion of the Tscherning Ellipse?

A

Oswalt Branch

81
Q

What is the most curved portion of the Tscherning Ellipse?

A

Wollaston Branch

82
Q

Vogel’s Formula For Plus Lenses

A

B.C. = Spherical Equivalent + 6.00

83
Q

Vogel’s Formula For Minus Lenses

A

B.C. = (Spherical Equivalent + 6.00) / 2

84
Q

Base Curve: Aspheric

A
  • The radius of curvature changes
    from the center to the edge.
  • Front curve for Plus RX flattens
    edge.
  • Front curve for Minus RX steepens
    toward edge.
  • Back curve for Minus RX flattens
    toward edge. ( Stock lens or special
    processing)
85
Q

Aspheric Advantages

A
  • Reduced lens thickness
  • Less bulge for Plus RX’s
  • Less magnification for plus RX’s
  • Less minification for minus
  • Lenses look and stay better in
    frames.
  • More frame choices
  • Improved peripheral vision
86
Q

Atoricity

A

An extension of aspheric design technology, allowing lens designers to optimize both sphere and cylinder powers.

87
Q

Atoric Surface

A
  • Asphericity varies for each power
    meridian.
  • Every sphere and cylinder
    combination is optimized.
88
Q

Surfacing

A
  • In conventional surfacing, a
    generator grinds away plastic on
    back of lens creating rough surface.
  • Final Ex on back surface is produced
    by rubbing against an aluminum
    tool and pad in fining and polishing
    steps.
89
Q

Free Form Machining

A
  • A natural diamond-cutting tool
    produces a very smooth surface
    that requires only light polishing to
    create transparency.
  • Each lens may require over 10
    million calculations to generate the
    data file for the free forming
    machine to create the lens surface.
  • The computer lens design is exact.
  • Control off-axis astigmatism
  • Perfect curves for sphere, cyl, and
    axis.
  • Create curves:
    -Aspheric
    -Atoric
    -Progressive
90
Q

Fitting Aspherics

A
  • Pre adjust the frame
  • Dot centers of pupils, measure
    height and subtract 1mm for every
    2 degrees of tilt or tilt head until
    pantoscopic tilt is eliminated before
    dotting pupils.
  • Use pupilometer for mono PD
  • Check cut out, prism cant be ground
    for decentration.
91
Q

AO Sola Vizio

A
  • 1.66 index
  • Unique atoric design
  • Flattened aspheric profile
  • Less mag
  • AR coated
  • -10.00 to +6.00D, 4.00D cylinder
92
Q

Optima Resolution

A
  • Aspheric front surface
  • Atoric back surface
  • Polycarbonate
  • ECM-9TM Extrusion Compression
    Molding
  • AR coated
  • Tantium non-tintable S/R coating
  • Tintable S/R coating
93
Q

Augen: Trinity Double Ashperic

A
  • Front aspherized in 2 meridians
  • Semi finished
  • Trivex
  • +6.00 to -10.00, up to 4.00D cylinder
94
Q

Wrap around sunglasses

A

+8.00 Base Curve

95
Q

Sola Spazio RX wrap lenses

A
  • Proprietary software and processing
    techniques.
  • Based on frame design, degree of
    frame wrap and patient PD.
  • Three different atoric designs to
    minimize peripheral blur.
  • +1.50 to -6.00 sphere with up to
    2.00D cylinder
  • Hard resin or polycarbonate
96
Q

Ultimate RX Wrap Around

A
  • Sola Contour Optics
  • 16.00D base curve with custom
    engineered frame.
  • Near constant vertex distance for all
    angles of sight.

OPT 2461L Ophthalmic Dispensing Lab 2 (4 decks)

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