Topography-Guided Photorefractive Keratectomy (TG-PRK) for Keratoconus (KC) With Simultaneous Collagen Cross-Linking (CXL): Excimer Laser

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Topography-Guided Photorefractive Keratectomy
(TG-PRK) for Keratoconus (KC) With Simultaneous
Collagen Cross-Linking (CXL) Excimer Laser

• Simon Holland
• David TC Lin
• ASCRS, Chicago, Illinois 2012
• No financial interests

Purpose

• To evaluate efficacy and safety of simultaneous
  TG-PRK for KC with simultaneous CXL

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Methods

• 127 keratoconus eyes underwent treatment with
  Allegretto excimer laser
• Treatment targeted at -1.25 post-op, with minimal
  residual stromal depth 300microns
• Epithelial removal by trans-epithelial laser
• Topography-guided PRK, T-CAT software, modified
  by TNT (topographical neutralization)
• Riboflavin 0.1 in dextran, until aqueous
  staining
• UV irradiation with riboflavin (up to 20 minutes)
• UV 370 um, 3mW/cm2 - 5.4 J/m2
• Hypotonic dextran if lt400 um
• Bandage contact lens, standard post PRK
• management

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TG-PRK CXL for KERATOCONUS
Pre-op 1.75-4.00x060 6 months post-op BSCVA
20/30- UCVA 20/30
RX
0.25-0.75x170 20/25
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TG-PRK CXL for KERATOCONUS
Pre-operative 6 months post-op UCVA 20/60
UCVA 20/40 MR 2.25-2.00X120 20/40- MR
-0.50-0.50X60 20/30-
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TG CXL PRK for KERATOCONUS
Pre-op -2.75-2.25x010 12 months
post-op BSCVA 20/20- UCVA
20/30-
RX 0.50-0.50x020 20/30-
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Results

• 99 eyes completed 6 months follow-up
• 53 (54) had 20/40 or better uncorrected visual
  acuity (UVA)
• 92 (93) had 20/40 or better best corrected
  visual acuity (BCVA)
• 51 (52) had BCVA improved, 32 (32) improved
  BCVA 2 lines or more, 33 (33) no change, 4 (4)
  lost 2 lines or more
• Mean astigmatism decreased -2.77D pre-op to
• -1.14D
• 4 had delay in epithelial healing with subsequent
  haze, 2 developed haze sufficient to reduce BCVA
  more than 2 lines, 1 had herpetic keratitis 3
  recovered pre-operative BCVA.
• Glare, halos, and difficulties with night driving
  decreased from 3.5 to 2.0 on a 4 point score
  (n25)

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Conclusions

• Simultaneous TG-PRK with CXL using customized TNT
  technique shows promise to improve both UCVA and
  BCVA in keratoconus patients with reasonable
  efficacy and safety
• Longer term results are needed to establish value
  and safety of combining attempted refractive
  correction and topographical regularization with
  collagen cross linking