RIGID GAS PERMEABLE LENS PROBLEM SOLVING
Progress Evaluation Procedures
Reduced Visual Acuity
Causes
:•Lens Design
•Lens Material
•Corneal Topography
•Lid Tension/Blink Quality
Complications:
•Reduced/Variable Vision & Flare
•Limbal Irritation/3&9 o’clock staining
•Lens Awareness
•Lens Dislocation
•Poor Corneal Alignment; excessive flattening & steepening with possibility of distortion
Management:
•Reduce Center Thickness
•Proper Edge Design (-lenticular < -1.50D/Plus; +lenticular > -5.00D)
•Bitoric > 2.50D corneal cylinder
•Lid Attachment Design
Causes:
•ATR astigmatism
•Displaced corneal apex
Management:
•Increase OAD or Steeper BCR
•Aspheric Design
Corneal Desiccation
Henry, Bennett, Forrest (AJO, 1986)
3 and 9 o’clock Staining to Fitting Relationship
Position
# Eyes 3 & 9 %Sup-Central 125 48 38
Interpalpebral 193 111 57
Inf-Central 46 34 73
Effects of too small versus too large
Refitting Contact Lens Wearers into RGPs
•Oxygen Permeability
•Modern Technology
•Vision in Spectacles
•Photographs/slides
•Videotapes – CLMA/RGPLI
(Clinical Pearls – Volume II)
44% from PMMA
46% from Hydrogel into RGP
10% from RGP/PMMA into Hydrogel