GP lens eye Rounds

KERATOCONUS: Small Diameter GP Lenses for Keratoconus Case

Will Skoog OD, FAAO

History

• 59-year-old Hispanic female, (+) keratoconus
• CC: blurry vision at all distances with glasses that are five years old. She attempted corneal GP wears over 20 years ago and experienced poor comfort.

Examination

• Entering Visual Acuities (VAs):
  OD with correction: 20/60
  OS with correction: 20/70
• Patient’s Rx via Lensometry:
  • OD: -7.00 -4.25 x 056 Add: +1.00D
  • OS: -10.75 -4.75 x 137 Add: +1.00D
• Slit Lamp Examination (SLE) OU
  • Inferior corneal thinning and steepening, (+) Fleischer Ring
• Corneal Tomography (Figure 1):

• • Dilated Fundus Examination (DFE):
    • unremarkable

 Decision-Making Process

• • She was hesitant about the size of scleral lenses.
  • The innovation in GP lens materials since she last wore GP lenses was emphasized.
  • Corneal elevation difference 78 microns OD and 71 microns OS
  • Paracentral cone
  • Corneal GPs were selected (keratoconic aspheric design)

Fitting and Evaluation

• • Initial diagnostic lens based on fitting guide:
    • OD: -11.00DS / BCR: 6.3mm / OAD: 8.7mm / std edge
      • SLE: Apical bearing with excessive edge lift 360˚
    • OS: -14.00DS / BCR: 6.0mm / OAD: 8.7mm / std edge
      • SLE: Apical bearing with excessive edge lift 360˚
  • Second diagnostic lens
    • OD: -14.00DS / BCR: 6.0mm / OAD: 8.7mm / std edge
      • SLE: Lid attached, feather touch on apex, mid peripheral bearing, minimal edge lift, decentered inferiorly with 1mm of movement.
      • Over-refraction: +5.00DS
      • VA: 20/20
    • OS: -17.00DS / BCR: 5.7mm / OAD: 8.4mm / std edge
      • SLE: Lid attached, feather touch on apex, mid peripheral bearing, minimal edge lift, decentered inferiorly with 1mm of movement.
      • Over-refraction: +7.75DS
  • Lens order
    • OD: -8.75DS / BCR: 6.0mm / OAD: 8.7mm / Hyper Dk F-S/A  green / flat 1 edge
    • OS: -8.50DS / BCR: 5.7mm / OAD: 8.4mm / Hyper Dk F-S/A blue / flat 1 edge
  • Dispense appointment
    • OD: -8.75DS / BCR: 6.0mm / OAD: 8.7mm /Hyper Dk F-S/A  green / flat 1 edge
      • VA: 20/25
      • SLE: lid attached, feather touch on apex, mid peripheral bearing, adequate edge lift, decentered inferiorly, 1mm of movement
    • OS: -8.50DS / BCR: 5.7mm / OAD: 8.4mm / Hyper Dk F-S/Ablue / flat 1 edge
      • VA: 20/30
      • SLE: lid attached, feather touch on apex, mid peripheral bearing, adequate edge lift, decentered inferiorly 1mm of movement
      • Final lens parameters – Rose K2
    • OD: -7.75DS / BCR: 6.0mm / OAD: 8.7mm / Hyper Dk F-S/A green / flat 1 edge
      • VA: 20/20
      • SLE: lid attached, feather touch on apex, mid peripheral bearing, adequate edge lift, decentered inferiorly, 1mm of movement
    • OS: -9.00DS / BCR: 5.7mm / OAD: 8.4mm / Hyper Dk F-S/A blue / flat 1 edge
      • VA: 20/25
      • SLE: lid attached, feather touch on apex, mid peripheral bearing, adequate edge lift, decentered inferiorly 1mm of movement

Clinical Pearls

• • Not all keratoconus patients need scleral lenses.
  • Corneal GPs are a great option!
  • Pay attention to the elevation map when deciding what contact lens to fit.