GP lens eye Rounds

POST-SURGICAL: Post Penetrating Keratoplasty Case – Mild/Moderate Astigmatism (left eye only)

Maria Walker OD, PhD, FAAO, FSLS

History

• HPI: dx with keratoconus for 10 years, s/p CXL OU in 2015, s/p PKP OS in 2021. Worn scleral lenses “for years”, poor fit with left eye since transplant.
• CC: irritation with habitual scleral lens OS. AWT: 12-16 hours; 7 days per week, after 6-10 hours OS lens is “pushing into the eye superiorly”. No visual complaints.
• Denies other visual disturbances or significant ocular history.
• Takes Levothyroxine and Lipitor. No ocular meds. Uses Systane gel PRN.

Examination and Fitting

• Entering vision
  • • i. OD: 20/20
    • ii. OS: 20/60
• Entrance testing: normal
  • • i. IOP: 10 OD, 12 OS
• Manifest Refraction
  • • i. OD: -9.75 -5.25 x 007, 20/40
    • ii. OS: -4.25 -4.00 x 162, 20/100
• Corneal Tomography (Figure 1)
• Slit Lamp Evaluation

• Habitual contact lens OS
• Fitting lens fit; d/c lens wear for 24 hours and return for scleral topography and new fit
• Scleral Lens Fitting:
  • • Scleral topography (Figure 2)
    • Lens Design: OS: Scleral/ -11.23 D / 6.818 BC / 16.0 DIA / 4892 SAG / no toricity / Acuity 200
      VA: 20/30- (plano SCOR)
    • Lens assessment (Figure 3): slight decentration, 200um apical clearance; >100um over graft/host interface; ~50um limbal clearance. Even landing with trace blanching IN quadrant – acceptable. Toric markers 3&9. No movement.
      Irregular astigmatism post-PKP OS – good fit, comfort, and vision with SL.
• Plan: Wear scleral lens and monitor q6-12 months. Pt educated on s/s of hypoxia and transplant rejection, advised to RTC sooner as needed.

Figure 1. Corneal topography OS. Ks: 45.20D/50.10D

Figure 2. Scleral topography of the left eye.

Figure 3. Lens evaluation after 4h wear. Slight IT decentration with toric markers at 3&9 (A). Apical clearance ~200um over central graft (B); Trace blanching IN (C); Adequate clearance over graft/host interface (yellow arrows show back lens surface) (D).

Decision-Making Process

• • Scleral lenses are a good option for post-transplant patients to limit corneal interaction.
  • Scleral topography can be a useful tool to design lenses and reduce remakes.
  • Reverse geometry designs are available but are not always indicated for post-transplant patients, especially if not highly oblate in shape.

Clinical Pearls

• • Post-transplant patients are at risk for hypoxia-related complications. High Dk materials can reduce sequelae (i.e., corneal edema, transplant rejection).
  • Collecting baseline data is important in scleral lens fitting on transplant eyes to monitor for changes.
  • Prolate designs can be helpful to keep center thickness low. The relatively steeper base curve in prolate designs will have more minus power. High plus powered lenses can create significant increases in central lens thickness that are not desirable in this hypoxia-risk population.

Beneficial Resources

1. 1. https://www.clspectrum.com/issues/2023/october/contact-lens-wear-after-corneal-transplantation/
   2. https://www.reviewofcontactlenses.com/article/postkeratoplasty-consider-sclerals
   3. Severinsky B, Behrman S, Frucht-Pery J, Solomon A. Scleral contact lenses for visual rehabilitation after penetrating keratoplasty: long term outcomes. Cont Lens Anterior Eye. 2014 Jun;37(3):196-202. https://pubmed.ncbi.nlm.nih.gov/24300196/
   4. Kumar M, Shetty R, Khamar P, Vincent SJ. Scleral Lens-Induced Corneal Edema after Penetrating Keratoplasty. Optom Vis Sci. 2020 Sep;97(9):697-702. https://pubmed.ncbi.nlm.nih.gov/32932397/
   5. Kumar M, Shetty R, Lalgudi VG, Vincent SJ. Scleral lens wear following penetrating keratoplasty: changes in corneal curvature and optics. Ophthalmic Physiol Opt. 2020 Jul;40(4):502-509. https://pubmed.ncbi.nlm.nih.gov/32436631/
   6. Guillon NC, Godfrey A, Hammond DS. Corneal oedema in a unilateral corneal graft patient induced by high Dk mini-scleral contact lens. Cont Lens Anterior Eye. 2018 Oct;41(5):458-462. https://pubmed.ncbi.nlm.nih.gov/29804935/