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

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

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

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

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

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

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

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

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

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

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 (100-120 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

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.