Intraoperative and Long-Term Corneal Biomechanical Changes
in Crosslinked Keratoconic Eyes
Elena Albé MD Elena Albé MD
Paolo Vinciguerra MD, Paolo Vinciguerra MD,
Silvia Trazza, MD Silvia Trazza, MD
EYE OCULISTICA Istituto Clinico Humanitas
Rozzano, MI, ItalyDirettore: Paolo Vinciguerra, MD
Boston, ASCRS, April, 2010
Financial discosure: I do not have any financial interest or relationship to disclose.
P253
AIM of the STUDYTo 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 witht 2 after epithelium removal preCXL sinet 3 after impregnation before UVA preCXL sine2t 4 after CKL procedure postCXL sinet 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
RESULTSCH and CRF
9,13
8,34
10,08
9,06
14,51
13,12
15,09
14,02
10,04
10,93
0
2
4
6
8
10
12
14
16
PRECXLwith BeforeUV afterRE-EPI
CH
CRF
p<0.05p>0.05 p<0.05 p<0.05
preCXL with
preCXL sine
AfterCXL
BeforeCXL
AfterRE-EPI
RESULTS RESULTS CHCH Corneal HysteresisCorneal Hysteresis
9,6810,32
15,18
12,48
9,57 9,61
0
2
4
6
8
10
12
14
16
CH
Statistical significance Statistical significance pp<0.05<0.05
p>0.05 p<0.05 p<0.05
PRE XLWITH EPI
PRE XLWout EPI
POST XLWout EPI
1 monthPOST XL
1 yearPOST XL
p>0.05
2 yearsPOST XL
p>0.05
CRFCRF Corneal Resistance Corneal Resistance FactorFactor
9,05 9,42
14,15
12,53
9,01 9,1
0
2
4
6
8
10
12
14
16
CRF
Statistical significance Statistical significance pp<0.05<0.05
p<0.05p<0.05p>0.05
PRE XLWITH EPI
PRE XLWout EPI
POST XLWout EPI
1 monthPOST XL
1 yearPOST XL
p>0.05
2 yearsPOST XL
p>0.05
RESULTSPeaks
247
187
229
153
202
139
172
131
0
50
100
150
200
250
PRECXLwith
postCXLsine
Peak 1
Peak 2
p<0.05p<0.05
preCXL with
preCXL sine
AfterCXL
AfterRE-EPI
p<0.05
Peak 1 and Peak 2
276228
493444 439
346
452
384
050
100150200250300350400450500
PRE XL 12mPOSTXL
Peak 1
Peak 2
p<0.05
p<0.05
6 monthsPOST XL
1 yearPOST XL
2 yearsPOST XL
p<0.05
p<0.05
RESULTS CORNEAL THICKNESS
462430 407 379
624
422 431 441 452
0
100
200
300
400
500
600
700
PRECXLwith afterRE-EPI 24 months ThinnestCorneaPoint
p>0.05 p<0.05p>0.05 p<0.05
p>0.05
p>0.05
p>0.05
preCXL with
preCXL sine
AfterCXL
BeforeCXL
AfterRE-EPI
1m 6m 12m 24m
p>0.05
RESULTS RESULTS IOPgIOPg
13,03 12,44
14,41
18,1
12,07 12,54
0
2
4
6
8
10
12
14
16
18
20
IOPg
Statistical significance Statistical significance pp<0.05<0.05
PRE XLWITH EPI
PRE XLWout EPI
POST XLWout EPI
1 monthPOST XL
p>0.05 p<0.05p>0.05 p>0.05
1 year POST XL
2 yearsPOST XL
p>0.05
RESULTS RESULTS IOPccIOPccStatistical significance Statistical significance pp<0.05<0.05
14,6413,45
9,92
16,71
14,25 14,32
0
2
4
6
8
10
12
14
16
18
IOPcc
PRE XLWITH EPI
PRE XLWout EPI
POST XLWout EPI
1 monthPOST XL
p>0.05 p<0.05 p<0.05 p>0.05
1 yearPOST XL
2 yearsPOST XL
p>0.05
CONCLUSIONWhat Happens during Cross Linking?
Epithelium removalIncreases 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;23:76-84The creation of a stromal flap can modify the biomechanical properties of the cornea, including a reduction of corneal hysteresis
CONCLUSIONWhat 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.