The Clinical And Experimental Study After Laser In Situ Keratomileusis Of Corneal Surface Elevation And Corneal Wound Healing

The clinical and experimental study after laser in situ keratomileusis ofcorneal surface elevation and corneal wound healing.The OrbscanII Topograph System is a useful instrument for the evaluation of anterior surface shape,posterior surface shape,anterior depth in corneal refractive surgeries.The Orbscanll Topograph System is very useful to study postoperative follow-up and safety evaluate of LASIK.But,the secondary keratoconus give a great impact in corneal refractive surgery field.The secondary keratoconu is a kind of progressive forward shift of corneal posterior surface elevation after LASIK.Because the Orbscanll Topograph System can evaluate the posterior surface shape,it can find the partial forward shift in corneal postetior and diagnosis the secondary keratoconu earlier.The etiological factor and pathogenesis of the secondary keratoconu is not sure,probably is the two factors of lability of corneal.biomechanics after LASIK and similarly nature keratoconus.At present,more investigation indicate that it is universial forward shift of corneal posterior surfacr shape after LASIK.It is not clear the relationship between progressive forward shift in corneal posterior surface shape and keratoconus.The Orbscanll Topograph System seems the most sensitive method to diagnosis subclinical keratonus.We investigate the changes in anterior and posterior surfaces after LASIK and find LASIK induces the forward shift of the cornea and the posterior surface is not progressive forward shift,without keratonus which indicate the realtively safety after LASIK.At present,the wound healing mechanism after LASIK is not clear.and it is more and more important in comprehending the wound healing mechanism.The wound hea -ling progress after early LASIK include earlier period corneal flap epithelization, the attachment between the corneal flap and matrix bed and the matrix reconstruction.At present,we can find the adhesion process between the corneal flap and resid -ual bed is weak in some cases when secondary LASIK occurred in 2~7 years after LASIK which may influence the cornea flap and residual bed on cornea intensity after LASIK.Histologic and ultrastructural findings in human corneas after successful laser in situ keratomileusis by Rumelt.The interface between the flap and bed was barely perceptible by light microscope.Reactive keratocytes were present at the wound interface in the corneas and in the area of the flap hing.The interface between the flap and bed was smooth and lacking keratocytes and collagen fibres by scanning electron microscope which may lead to the swollen and wavy adhesion between the corneal flap and residual bed on corneal intensity after LASIK.Therefore,more and more impo -rtant task is to find the drug which induce the corneal wound healing and adhesion between the corneal flap and residual stroma bed.The corneal stroma wound healing process is a complicated pathological and physiological progress,which include corneal fibroblast migration,proliferation and corneal stroma reconstruction.Corneal stroma involved corneal fibroblast and extrac -ellular matrix,the corneal strom construction is the mutual results between the corne -al fibroblast and ECM.Most of growth factors had taken part in the corneal wound healing.We cultured primary rabbit corneal fibroblasts(RCF) and exposed RCF to rhPDGF-BB and/or rhb-FGF at various concentration respectively.The proliferation of the cells were studied with MTT assay.Meanwhile,we investigate the effects of recombinant human PDGF-BB on the proliferation and cell cycle of cultured rabbit corneal fibroblasts.By these experiment we hope it can help the application of recombinant human platelet-derived growth factor-BB and basic fibroblast growth factor in the corneal wound healing.l.Changes in the anterior and posterior surfaces after Laser insitu keratomileusis To use Orbscanll for measuring the anterior and posterior surface of corneal elevation after laser in situ keratomileusis (LASIK), providing data for the safety of LASIK.Methods:This study included 210 myopic and myopic astigmatism of 110 consecutive cases.Subjects were divided into 3 groups according to their preoperative level of myopia:GroupI:<-6.0D,70 eyes;Group II: -6.25D~ -10.0D, 70 eyes;GroupIII:>-10.25D, 70 eyes;Their anterior and posterior surface elevation were detected by Orbscan II after LASIK,their data were analyzedstatistically.Results:There was no significant difference among 3 groups in distance from the top point of the anterior surface to the perfect spherical surface(diff value) between 3 to 6 months and 6 to 24 months after Lasik.There was also no significant difference between group I and II in distance from the posterior surface elevation to the perfect spherical surface(diff value) between 3 to 6 months and 6 to 24 months after Lasik.There was a significant difference in group III in distance from the posterior surface elevation to the perfect spherical surface (diff value) between 3 to 6 months and 6 to 24 months after Lasik.AH cases were no progressive comeal forward shift and iatrogenic keratectasia.Conclusion:LASIK induces the forward shift of the cornea.The Orbscan II Topograph System is very useful to study anterior surface shape,poste -rior surface shape,postoperative followup and safety evaluate of LASIK.2.The effects of recombinant human platelet derived growth factor -BB and basic fibroblast growth factor on the proliferation of culturedrabbit corneal fibroblast.To observe the effects of recombinant human plateletderived growth factor-BB and basic fibroblast growth factor on the prolifertion of cultured rabbit comeal fibroblasts.Methods:Rabbit comeal fibroblasts were exposed to rhPDGF-BB and/or rhb-FGF at various concentration for 1> 2 s 3days respec -tively.The proliferation of the cells were studied with MTT assay.Results:The proliferating effects of cultured rabbit comeal fibroblast with either recombinant human platelet derived growth factor-BB or basic fibroblast growth factor were significantly more than that of control at the 24 th,48th and 72th hours (p<0.01). RhPDGF-BB at 10~100ng/ml or rhbFGF at 0.1~10ng/ml promoted RCF growth in a dose and time dependant way(p<0.01).The proliferating effects of rhb-FGF at 100 ng/ml on cultured rabbit comeal fibroblast decreased.RhPDGF-BB at lOng/ml and rhb-FGF at 0.1 ng/ml showed stronger effects on cultured rabbit comeal fibroblasts growth than both used individually(p<0.05).Conclusion: RhPDGF-BB and/or rhb -FGF can promote the proliferation of the cultered rabbit comeal fibroblast.3.The Effects of recombinant human PDGF-BB on the prolifera...