Lecture Notes on Fitting Corneal and Intra-Limbal Lenses

Goals in Lens Fitting

• Ideal Pattern: Slight apical pooling or three-point touch
  • Three-point touch: Lens touches in three locations (center, two in mid-periphery)
  • Creates four zones:
    • Center: Light apical touch
    • Paracentral: Pooling
    • Mid-peripheral: Bearing zone
    • Peripheral: Clearance for tear exchange

Assessment of Lens Fit

• Left Fit Example:
  • Mild to moderate apical pooling
  • Paracentral pooling without bubbles
  • Mid-peripheral bearing ring
  • Peripheral clearance excessive at six, minimal at three and nine
• Right Fit Example:
  • Harsh touch on cornea, leads to SPK and scarring
  • Tear meniscus breaks at six with excessive edge lift

Differentiating Touch

• Harsh vs Light Touch:
  • Harsh: Distinct border between center and paracentral pooling
  • Light: Fuzzy, hard-to-define border

Characteristics of Intra-Limbal GP Lenses

• Larger than corneal GP (10-12 mm diameter)
  • Less movement on the eye
  • Edges tucked under eyelids for comfort
  • Improved stability and centration

Clinical Practice

• Switching from Corneal GP to Intra-Limbal GP:
  • Consider when facing comfort issues, poor centration, or irregular patterns
• Fitting Strategy:
  • Use the fit guide, start with deep or average K
  • Modify based on fluorescein pattern using a red filter
  • Over-refraction only after achieving light touch or slight pooling
  • Document lens fit and consult with a specialist

Lens Modifications

• Optic Zone Adjustment:
  • Smaller optic zones reduce paracentral pooling and bubbles
  • Helps snug fit around cones
  • Taught by Dr. Bennett at GPLI Residency Day