Plastic Lens Materials Flashcards

1
Q

CR39 (Essilor Orma)

A
N Value = 1.498
V Value = 58
Specific Gravity = 1.32
CVF = 1.05
Reflectance = 3.97%
UV cut off = 355nm
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2
Q

Key features and benefits of CR39

A
  • Excellent Optics
  • Low cost
  • Easy to tint
  • Lowest reflectance so doesnt need MAR
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3
Q

Disadvantages of CR39

A
  • Thickness
  • Shatters under high impact into hooked shards
  • Not very scratch resistant
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4
Q

Trivex

A
N value = 1.53
V value = 45
Specific Gravity = 1.11
CVF = 0.99
Reflectance = 4.39%
UV Cut off = 400nm
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5
Q

Key features and Benefits of Trivex

A
  • High impact resistance
  • Blocks 100% of UVA & UVB
  • Higher V value than polycarbonate
  • Lightest lens material available
  • Good chem resistance
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6
Q

Disadvantages of Trivex

A
  • Tinting not possible
  • Slightly thicker than polycarbonate
  • Scratches easily
  • Difficult to glaze
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7
Q

Polycarbonate (Essilor airwear)

A
N = 1.59
V Value = 30
Specific Gravity = 1.21
CVF = 0.89
Reflectance - 5.19% 
UV Cut off = 385nm
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8
Q

Key features and Benefits of Polycarbonate

A
  • High impact resistance
  • Lighter than high index plastic lenses
  • Thinner than trivex
  • Good UV protection
  • Thermoplastic - can be remoulded
  • Good for Supra and Rimless as you can drill into it and cut grooves
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9
Q

Disavantages of Polycarbonate

A
  • Not good for chem resistance - if used with acetone, lens goes milky
  • Low V value means more dispersion
  • Not very scratch resistant
  • Difficult to tint
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10
Q

1.6 Plastic (Essilor Ormix)

A
N = 1.60
V Value = 42
Specific Gravity = 1.30
CVF = 0.87 
Reflectance = 5.33% 
UV Cut off = 395nm
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11
Q

Key features and Benefits of 1.6 Plastic

A
  • Thin and lightweight
  • Less costly than 1.74 plastic
  • Good UV protection
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12
Q

Disadvantages of 1.6 Plastic

A
  • Low V value
  • Difficult to tint
  • Flatter so more reflections (MAR coated)
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13
Q

1.67 Plastic (Essilor Stylis)

A
N = 1.67
V Value = 32
Specific Gravity = 1.36
CVF = 0.78
Reflectance = 6.29%
UV Cut off = 395nm
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14
Q

Key features and Benefits of 1.67 Plastic

A
  • Cheaper than 1.74
  • Good UV protection
  • Thin
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15
Q

Disadvantages of 1.67 Plastic

A
  • Low V value
  • Diff to tint
  • Flatter so more reflections (MAR coated)
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16
Q

1.74 Plastic (Essilor Lineis)

A
N = 1.74
V Value = 32
Specific Gravity = 1.46
CVF = 0.71
Reflectance = 7.29% 
UV Cut off = 395nm
17
Q

Key features and Benefits of 1.74 Plastic

A

Thinnest readily available plastic lens (1.76 lenses are available)

18
Q

Disadvantages of 1.74 Plastic

A
  • Diff to tint

- Low V value causes increased dispersion and TCA