GP lens eye Rounds

KERATOCONUS: Intralimbal GP Piggyback Case

Matt Kauffman OD, FAAO, FSLS

History

• HPI: 49-year-old caucasian male with history of keratoconus. Underwent corneal cross-linking (CXL) surgery: OD – Dec. 2023; OS – Jan. 2024. Currently wearing piggyback intralimbal gas permeable (GP) lenses with soft contact lenses (CL).
• CC: Blur at distance with current contact lenses.

Examination

• Entering visual acuities with correction:

OD: 20/30-1
OS: 20/25-1

• Manifest Refraction:

OD: -6.25 – 5.00 x 013 20/70-1
OS: +0.25 – 0.50 x 050 20/30

• Slit Lamp Examination:

• Corneal Topography (Figure 1)

Kmax: 65.5 D; Kmax: 51.5 D

Figure 1: Corneal topography maps for both OD and OS

• Corneal Pachymetry (Figure 2)

Figure 2: Corneal Pachymetry OD (left) and OS (right)
OD: Minimum corneal thickness: 352 µm
OS: Minimum corneal thickness: 466 µm

Decision-Making Process

Patient preferred to continue wearing piggyback intralimbal lenses due to improved comfort with the soft contact lens and improved vision with GP lenses. He had a negative experience with scleral lenses previously.

Fitting and Evaluation

• • Habitual GP and Soft Lenses
    • OD: Intralimbal = 7.50mm BCR/11.2mm OAD/-1.50D
      VA (with piggyback): 20/30-1
      SLE: Central touch, mid-peripheral alignment, adequate edge lift (Figure 3) OR: +0.50DS
      Soft lens: 8.4mm BCR/14.0mm OAD/Plano
      SLE: Adequate movement/centration

Figure 3: Right eye piggyback fitting relationship

• • OS: Intralimbal = 7.67mm BCR/11.2mm OAD/-2.25D VA: 20/25-1
    SLE: Central and mid-peripheral alignment,, adequate edge lift; OR: +1.25D
    Soft lens: 8.4mm BCR/14.0mm OAD/Plano
    Adequate movement/centration
    Plan: Order new OD and OS lenses
• First dispense:
  • OD: Intralimbal with soft CL = 7.18mm BCR/11.2mm OAD/-3.00D VA: 20/20-1
    • SLE: Improved fit centrally, light touch, mid-peripheral alignment, adequate edge lift
  • OS: Intralimbal with soft CL = 7.67mm BCR/11.2mm OAD/-1.00D VA: 20/20-2
    • SLE: Central and mid-peripheral alignment adequate edge lift
  • Assessment: Improved comfort and vision with new lenses
• One week follow-up visit:
  • Assessment: Right lens does not stay centered all the time. Vision is good.
  • OD: Intralimbal with soft CL = 7.18mm BCR/11.2mm OAD/-3.00D; OR: +0.25D
    • SLE: Light touch, mid-peripheral alignment, excessive edge lift
  • OS: Intralimbal with soft CL = 7.67mm BCR/11.2mm OAD/-1.00D; OR: Plano
    • SLE: Central and mid-peripheral alignment, adequate edge lift
  • Plan: Steepen OD lens BCR 0.50 D; steepen edge 1 step
• Second dispense:
  • Improved vision OD. Lens feels more comfortable.
  • OD: Intralimbal with soft CL = 7.11mm BCR/11.2mm OAD/-3.25D VA: 20/20-1
    • SLE: Alignment centrally and mid-periphery; adequate edge lift (Figure 4)
  • OS: Intralimbal with soft CL = 7.67mm BCR/11.2mm OAD/-1.00D VA: 20/20
    • BCR: Alignment centrally and mid-periphery; adequate edge lift

Figure 4: Final right eye fitting relationship

Clinical Pearls

• Piggyback lenses are a great option for patients who cannot tolerate a rigid lens or when an ideal lens-to-cornea fitting relationship cannot be obtained.¹
• Utilize highly oxygen-permeable soft and GP materials.
• Consider using a moderately high plus soft CL (e.g. +6.00 D) for patients with an inferior apex or when the GP lens decenters.²
• Both lenses should move independently of each other.
• The soft contact lens will contribute 20% to 25% of the power of the lens on average.³

Sources

1. 1. Kauffman MJ, Bennett ES, Szczotka-Flynn L. Keratoconus. In Bennett ES, Henry VA (eds). Clinical Manual of Contact Lenses (5th ed.), Philadelphia, Wolters Kluwer:558-643.
   2. Szczotka-Flynn L. Optimizing GP lens designs in the clinical management of irregular astigmatism. Presented at: The 2010 Global Specialty Lens Symposium; January 2010; Las Vegas, NV.
   3. Brazeau D. Fitting and effective power of soft lenses in piggyback system. Presented at: The 2009 Global Specialty Lens Symposium; January 2009; Las Vegas, NV.