Lenses Information

TYPES OF LENSES

Single Vision Lenses

These lenses are used to correct vision at only ONE field view. Distance Vision Only (DVO) lenses are designed to correct vision at distance, to see far. Near Vision Only (NVO) lenses are used to see clearly at near, for reading. Intermediate lenses are designed for computer usage.

  • Pros: Easier and faster to adapt and less expensive, compared to other lenses.
  • Con: Not suitable for Presbyopia patient.

 

Bifocals Lenses

These lenses are used to correct vision at TWO fields of view; distance and near. Bifocals lenses designed to correct Presbyopia and disorders of accommodation.

  • Pros:
    • Less expensive than Progressive lenses
    • No need to have two pair of eyeglasses
  • Cons:
    • Visible line
    • Not suitable for computer user since it is missing intermediary vision

 

Progressive Lenses (PAL)

These lenses are used to correct vision at all distance. PALs are designed to correct Presbyopia.

  • Pros:
    • Invisible line, good for cosmetic reason 
    • Suitable for computer user
  • Cons:
    • More expensive
    • Take longer to adapt than bifocals lenses

LENS MATERIALS

CROWN GLASS

Pros:

  • Scratch resistant lenses
  • Clear and superior optics

Cons:

  • Non-Tintable
  • Very heavy
  • not impact resistant (could shatter)
  • Widely not available (longer turnaround time)

POLYCARBONATE LENS

Pros:

  • Same material used for bullet proof glass
  • Very impact resistance, more suitable for children (used safety and sport glasses)
  • UV protection
  • Resist scratch than plastic lens
  • About 25% thinner and lighter than plastic lens

Cons:

  • Lower optical quality than plastic lens
  • Less likely to absorb tint
  • More expensive than plastic lens

TRIVEX LENS

Pros:

  • Impact resistance than polycarbonate lens
  • Better optical quality than polycarbonate lens (much clearer)
  • Tintable
  • The lightest material
  • UV proctection
  • Very strong (most ideal for drill mounts)

Cons:

  • More costly than polycarbonate lenses

 

CR-39 (PLASTIC) LENS

Pros:

  • About 50% lighter than glass lens
  • Tintable
  • Widely available and the most cost effective
  • Less likely to fog

Cons:

  • Less scratch resistant (unless hard coating applied)
  • not suitable for high power RX due to thicker lens

HI-INDEX LENS

Pros:

  • Available in hi-index 1.60, 1.67, 1.74
  • The higher the index, the thinner the lens are
  • Better optical quality than polycarbonate

Cons:

  • Experience more glare and reflections (correctable by Anti-Reflective coating)
  • More expensive

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