1. Elena Albé MD Paolo Vinciguerra MD, Silvia Trazza, MD
Boston, ASCRS, April, 2010
Intraoperative and Long-Term Corneal Biomechanical Changes in Crosslinked Keratoconic Eyes
Elena Albé MD
Paolo Vinciguerra MD,
Silvia Trazza, MD
Financial discosure: I do not have any financial interest or relationship to disclose.
EYE OCULISTICA
Istituto Clinico Humanitas
Rozzano, MI, Italy
Direttore: Paolo Vinciguerra, MD

2. CROSS LINKING PROCEDURE
AIM of the STUDY To analyze the biomechanical properties of 24 keratoconic corneas Amsler grade II undergoing CXL and correlate the intraoperative biomechanical and geometrical change
t 1 baseline preCXL with t 2 after epithelium removal preCXL sine t 3 after impregnation before UVA preCXL sine2 t 4 after CKL procedure postCXL sine t 5 after reepithelialization postCXL with
1,6,12 and 24 months after CXL by means of CSO TOPOGRAPHER OCULAR RESPONSE ANALYZER PENTACAM
CROSS LINKING PROCEDURE
2% Pilocarpine drops and antipain meds 30 min before CXL.
Oxybuprocaine hydrochloride 0.2% 5 min before CXL.
LASER TEST UVA meter
Laser  370±5 nm
Power 3 mW/cm2 (= 5.4 j/cm2)
RICROLIN riboflavin 0.1% solution instillation each minute for 30 min
Riboflavin check absorption in anterior chamber (flare).
UVA Light Corneal irradiation PESCKE X-Linker 7.5 mm Ø.
RICROLIN instillation 6 times of 5 min each
Bandage soft CL application and levofloxacin eyedrops

3. RESULTS CH and CRF preCXL with preCXL sine Before CXL After CXL After
RE-EPI

4. RESULTS CH Corneal Hysteresis
Statistical significance p<0.05
RESULTS CH Corneal Hysteresis
Lo studio della variazione del parametro di isteresi corneale= viscosità della cornea mette in luce 1. 2. 3. 4.
PRE XL
WITH EPI
PRE XL
Wout EPI
POST XL
Wout EPI
1 month
POST XL
1 year
POST XL
2 years
POST XL
p>0.05
p<0.05
p<0.05
p>0.05
p>0.05 4

5. CRF Corneal Resistance Factor
Statistical significance p<0.05
Lo studio della variazione del parametro di fattore di resistenza corneale = elasticità della cornea mette in luce 1. 2. 3. 4.
PRE XL
WITH EPI
PRE XL
Wout EPI
POST XL
Wout EPI
1 month
POST XL
1 year
POST XL
2 years
POST XL
p>0.05
p<0.05
p<0.05
p>0.05
p>0.05 5

6. RESULTS Peaks preCXL with preCXL sine After CXL After RE-EPI p<0.05

7. Peak 1 and Peak 2 6 months POST XL 1 year POST XL 2 years POST XL

8. RESULTS CORNEAL THICKNESS
p>0.05
p>0.05
p>0.05
p>0.05
p>0.05
p>0.05
p<0.05
p<0.05
preCXL
with
preCXL
sine
Before
CXL
After
CXL
After
RE-EPI 1m 6m
12m
24m

9. RESULTS IOPg Statistical significance p<0.05 PRE XL WITH EPI PRE XL
Wout EPI
POST XL
Wout EPI
1 month
POST XL
1 year
POST XL
2 years
POST XL
p>0.05
p>0.05
p<0.05
p>0.05
p>0.05

10. RESULTS IOPcc Statistical significance p<0.05 PRE XL WITH EPI
Wout EPI
POST XL
Wout EPI
1 month
POST XL
1 year
POST XL
2 years
POST XL
p>0.05
p<0.05
p<0.05
p>0.05
p>0.05

11. CONCLUSION What Happens during Cross Linking?
Epithelium removal
Increases corneal curvature
Reduces corneal thickness
Reduces light detected during applanation peaks
Does not influence corneal biomechanical properties
CH and CRF
MullerLJ, Pels E, Vrensen GFJM. The specific architecture of the anterior stroma accounts for the maintenance of corneal curvature. BJO.2001;85:437-43
The specific architecture of the most anterior part of the corneal stroma ( microns) has been suggested to be responsible for the stability of the corneal shape.
Gatinel D, Chaabouni S, Adam PA, Munck J, Puech M, Hoang-Xuan T. Corneal hysteresis, resistance factor, topography, and pachymetry after corneal lamellar flap. JRS.2007;23:76-84
The creation of a stromal flap can modify the biomechanical properties of the cornea, including a reduction of corneal hysteresis

12. CONCLUSION What Happens after Cross Linking?
T-dextran and riboflain dehydrate cornea along CXL
Cornea dehydration affects biomechanical properties
increases CH and CRF
reduces light detected during applanation Peaks
Rehydration and corneal oedema affect corneal biomechanical properties
Reduces CH and CRF
Reduces light detected during applanation Peaks
Peak 1 and Peak 2 increase after CXL, suggesting a reduction in KC deformation.
IOPg and IOPcc remain higher till steroid admin.
At 24 months, CXL does not induce any change in IOP.
CXL induces a significant reduction in corneal thickness and total corneal volume, however corneal thickness recovers at 1 year follow-up.