Fitting Corneal and Intra Limbal Lens Designs

Ideal Patterns for Lens Fit

• Objective: Slight apical pooling or three-point touch.
• Three-Point Touch: Touch in three locations - one in the center and two in the mid-periphery.

Zones of the Lens Fit

1. Center Portion: Light apical touch.
2. Paracentral Pooling: Ring of paracentral pooling.
3. Mid Peripheral Bearing Zone: Where the lens rests.
4. Peripheral Clearance: Ensures tear exchange and ocular health.

Describing a Lens Fit

• Mild to Moderate Apical Pooling: Paracentral pooling (no bubbles).
• Mid Peripheral Bearing: Ring visible.
• Peripheral Clearance: Excessive at 6 o'clock, minimal at 3 and 9 o'clock.
• Avoid harsh touch on the cornea to prevent SPK (superficial punctate keratitis) and scarring.

Differentiating Harsh vs. Light Touch

• Harsh Touch: Distinct border between center portion and paracentral pooling.
• Light Touch: Fuzzy border, indicative of healthy tear exchange.

Intra Limbal GP Lenses

• Size: 10 to 12 mm in diameter (bigger than traditional corneal GP).
• Comfort: Edges tucked under the eyelids, less movement, more stable.
• Indications for Use: Improve comfort, centration, and stability when traditional corneal GP lenses fail.

Adapting to Irregular Corneas

• Objective: Maximize patient's vision without harming the eye.
• Monitoring: Ensure no SPK, staining, or other issues.

Fitting Process

1. Follow Fit Guide: Start with deep K / average K and modify based on fluorescein pattern.
2. Wrattan Filter: Enhances fluorescein pattern visibility for assessment.
3. Over-Refraction: Only after achieving slight touch/pooling to ensure accuracy.
4. Documentation and Consultation: Document fit, conduct over-refraction, and consult for modifications.

Parameter Modification

• Optic Zone: Smaller optic zone helps reduce paracentral pooling and bubbles.
  • Example: Adjust optic zone to snugly fit around the cone.