Pachymetry Fluctuations During Corneal Crosslinking (CXL)

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Pachymetry Fluctuations During Corneal
Crosslinking (CXL)

• Dr. Arthur Cummings1
• Dr. Eugene Ng2
• 1) Wellington Eye Clinic, Dublin, Ireland
• 2) Royal Victoria Eye and Ear Hospital, Dublin,
  Ireland

No financial disclosures
ASCRS, Boston 2010
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Corneal collagen crosslinking is a widely used
treatment modality for keratoconus
Current protocols recommend 400 microns of
pre-treatment corneal thickness due to potential
endothelial damage in thinner corneas
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However, there are no studies looking at
intra-procedural pachymetry during CXL.

• Medio-Cross (Riboflavin 0.1, Dextran 500 20) is
  supposed to be isotonic.
• We report intra-procedural pachymetry (at 5
  minute intervals) using Medio-Cross during CXL

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Results

• 15 consecutive patients who underwent CXL also
  had intra-procedural pachymetry measurements at 5
  minute intervals.
• All patients had pre-operative pachymetry of gt400
  microns on both optical and ultrasound
  pachymetry.

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Results
Medio-Cross instillation
Pre-op Post epithelium 5 mins 10 mins
15 mins 20 mins Pre UVA Pachy Removal

• A wide variation in the loss of corneal thickness
  was noted (15-36).

Hypotonic Riboflavin added
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Discussion

• Corneal desiccation may have accentuated
  thinness of the cornea as measured by
  ultrasound pachymetry (speed of sound in denser
  medium).
• The safe level of corneal thickness throughout
  the procedure (as measured by ultrasound
  pachymetry) needs to be defined if endothelial
  damage is to be avoided.

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Discussion

• It is possible that the variable effect of
  Medio-Cross on corneal thickness may be related
  to the varying effect of CXL efficacy.
• The effects of hypotonic riboflavin (apart from
  increasing corneal thickness) may provide a false
  sense of safety
• The relative efficacy of CXL where hypotonic
  riboflavin is used is unknown.