Rabbits Of Different Cutting Thickness After Lasik Mmp Expression In Rabbits

Objective To study the influence of different residual comea bed of laser in situ kera -tomileusis(LASIK)on the collagenic construction of cornea through investigating the ex -pression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in cornea cell for different residual stroma bed after LASIK for six months.Methods Forty four New Zealand white rabbits(88 eyes) were divided into four gr-oups at random.Eleven eyes in group A were controls.Rabbits in groups B,C and D were performed LASIK with residual stroma bed of the cornea 70%,50%and 30%re -spectively.Six months after operation,the posterior best fit sphere were analysised in co -rnea topography,aquired the cornea tissue to perform indirect enzyme-linked immuno-ab sordent assay(ELISA) for the quantity of Gelatinase,zymography for the activities of Gelatinase, reverse transcription-polymerase chain reaction(PT-PCR) for the expression of tissue inh-ibitors of metalloproteinase(TIMP-2)mRNA.The changes of cornea structures were obse-rved by transmission electron microscope.Results 1,Indirect enzyme-linked immuno-absordent assay(ELISA) proved that MM-2 and MMP-9 were expressed in cornea cell in groups of A,B,C,D after LASIK fo -r si-x moonths,and MMP-2 was no significant difference between the four groups(F= 0.456,P＞0.05),MMP-9 was no significant difference too(F=1.676,P＞0.05).2,Zymography for the activity of gelatinase showed that the activity of MMP-2 was ex -pressed in cornea cell in groups of A,B,C,D after LASIK for six moonths,and th ere was no significant difference between the four groups.The activity of MMP-9 was not expressed in four groups.3,Reverse transcription-polymerase chain reaction(PT-PCR) showed that the TIMP-2 mRNA RNA was expressed in cornea cell in groups of A,B,C,D after LASIK for six mon -ths,and there was no significant difference between the four groups(F=0.003,P＞0.05). The expression of the TIMP-2 mRNA was increase with the artherectomy intensity.4,Coreal topography showed that there were no keratoconus in four groups.The Diff(d -ifference) value of posterior cornea before operation was no significant differen-ce betw -een the four groups(F=0.361,P＞0.05).Comparison the Diff value of posterio-r cornea wa -s significant difference between before and after operation in groups C and D(P＜0.05), there was no significant difference in group B(t=2.00,P＞0.05).Increase of posterior cornea prominence was significant difference(F=356.7,P=0.000).The Diff and raise of pr -ominence were increased in posterior cornea with the artherectomy intensity.5,Transmission electronic microscopy showed that the arrangements of collagen fiber ne -at and rule in the cornea of groups B,C,D after LASIK for six months.There have no difference with the normal cornea.There were no abnormal phenomenon,for example,no inc -rease and swell of chondriosome in fibroblast,no vocuolus and no increase of rough e ndoplasmic reticulum in fibroblast.Conclusions The rabbit normal cornea has MMP-2 and MMP-9 expression;MMP-2 a -nd MMP-9 were expressed in cornea cell in groups of B,C,D after LASIK for six moonths,and there were no significant difference between the four groups.If has the ke -ratoconus occurrence because surgery itself causes the collagen degeneration to increase by no means causes,possibly it is related to the heredity susceptivity and biological m -echanics,affects the mechanism pending further to study specifically.