UNIT 1: Contact Lens Inspection & Verification

Question 1

Total Diameter

Answer 1

• Tolerance: +/- 0.10 mm
• V- Channel, Slip or Slot Gauge
• Measuring Magnifier
• Projection Magnifier

Question 2

Optical Zone Diameter

Answer 2

• Tolerance:
  Blend = +/- 0.2mm
• Measuring Magnifier
• Projection Magnifier

Question 3

Peripheral Curve Width

Answer 3

• Tolerance:
  No Blend & Light Blend = +/- 0.05mm
  Medium & Heavy Blend = +/- 0.1mm
• Measuring Magnifier
• Projection Magnifier

Question 4

Lens Power Back Vertex Power

Answer 4

• Tolerance:
  0.00 - 5.00D = +/- 0.12D
  5.00 - 10.00D = +/- 0.18D
  10.00 - 15.00D = +/- 0.25D
• Lensmeter
• Projection Lensmeter

Question 5

Center Thickness

Answer 5

• Tolerance: +/- 0.02mm
• Thickness Gauge

Question 6

Central Posterior Curve (CPC) / Base Curve

Answer 6

• Tolerance: Radiuscope
• PMMA 0.025
• RPG 0.050
• Keratometer:
  Lens Holder
  Conta-Check

Question 7

Radiuscope

Answer 7

• Clean and dry lens
• Float lens concave side up on lens holder
• Move stage to center green spot
• Turn focusing knob to locate aerial image ( usually
  between 7.00 & 8.00mm) & center.
• Turn focusing knob (scale moving toward zero)
  until real image is focused.
• Set scale to zero
• Turn focusing knob until aerial image is focused
  and note reading on scale.

Question 8

Blend

Answer 8

• Tolerance:
  Subjective, Light, Medium, and Heavy
• Measuring Magnifier
• Projection Magnifier
• Profile Analyzer
• Light Reflection Technique

Question 9

General Inspection

Answer 9

• Defects
• Methods:
  
  • Measuring Magnifier
  • Slit Lamp with Slide or Wet Cell
  • Black Background/ White Background

Question 10

Parameters

Answer 10

• Total Diameter : Measuring Magnifier
• Power: Lensometer
• Central Posterior Curve

Question 11

Advantages and Disadvantages of In-Office Modification

Answer 11

• Time
• Convenience
• Control
• Image
• Equipment
• Breakage

Question 12

Inspection & Verification Equipment

Answer 12

• Measuring Magnifier
• Projection Magnifier
• Diameter Gauge
• Thickness Gauge
• Radiuscope
• Lensometer
• Profile Analyzer or Fluorescent Tubes

Question 13

Modification Equipment

Answer 13

• Unit with variable speed motor ( 500 to 1000 rpm)
• Holders:
  
  • Mounting Tool
  • Suction Cup
  • Spinner
  • Block & Stylist
• Adhesives:
  
  • Double-faced tape, wax, pitch

Question 14

Tools

Answer 14

• Materials:
  
  • Diamond
  • Brass
  • Delrin
  • Stone
• Radius
• Conical:
  
  • 90, 70, & 60
• Drum
• File
• Emory Board
• Razor Blade

Question 15

Pads

Answer 15

• Tape
• Pellon
• Suede Cloth
• Mole Skin or Foam
• Velveteen

Question 16

Polishes

Answer 16

• X Pal
• Alox
• Sil 02 Care
• Boston Finishing Polish

Question 17

What should you avoid when using polishes?

Answer 17

Alcohol and Ammonia

Question 18

What shouldn’t you use on RPG lenses?

Answer 18

Silvo

Question 19

Diameter Reduction

Answer 19

• Reduce 0.1 to 0.3 oversize
• Mounting Tool
  
  • File
  • Emery Board
  • Razor Blade
• Conical Tool
  
  • Lens Holder

Question 20

Peripheral Curves

Answer 20

• Grind:
  
  • Diamond or Stone with Water
• Polish:
  
  • Brass or Delrin Tool with hard pad.
  • Add pad thickness ( 0.2mm) to tool radius to
    determine the radius generated.
• Blend:
  
  • Brass or Delrin Tool with soft pad (0.4mm
    Thick).
  • Use compensated radius half way between
    curves to be blended.

Question 21

Edge

Answer 21

• Thickness Reduction:
  
  • Conical Tools
• Polishing
  
  • Flat Pad
  • Drum
  • Rolling Sponge

Question 22

Power Changes

Answer 22

• Minus ( Add up to 0.50D ):
  
  • Flat Pad
  • Manual
• Plus ( Add up to 0.25D ):
  
  • Flat Pad
  • Drum

Question 23

Surface Polish

Answer 23

• Verify or Neutralize Parameters
• Methods:
  
  • Flat Pad
  • Drum
  • Manual
• Check Power and Base Curve