Expression of transforming growth factor-β, α-smooth muscle actin and wound healing characteristics of rabbit cornea after sub-Bowmans leratomileusis, photorefractive keratectomy, laser in situ keratomileusis

Background There are a lot of studies about the wound healing charateristics of cornea after SBK with femtosecond laser.In our study,mechanical microkeratome was preferred for corneal flap.We observed the proliferation of keratocytes by investigating the myofibroblast ( MF) activity. Objective The study was to compare the morphologic and histological changes in the cornea after sub-Bowmans keratomileusis ( SBK) with photorefractive keratectomy ( PRK) and laser in situ keratomileusis ( LASIK) by investigating the express of transforming growth factor-β( TGF-β) and α-smooth muscle actin( α-SMA) and to investigate the wound healing characteristiCs of cornea after SBK. Methods Twenty-seven adult New Zealand white rabbits were randomly assigned into group A,B and C.SBK waa performed on the right eyes of each rabbit in group A,LASIK for group B and PRK for group C.All the left eyes were used as the normal control group.Histological examinations by light microscopy were performed on day 7,1 months,3 months after surgery.The expression of α-SMA and TGF-β and the number of activated MF were assessed by immunohistochemiatry. Results In SBK group,corneal epithelium cells proliferation around the wound was seen and the numbers of active fibroblasts were increased after surgery.The expression of α-SMA or TGF-β around the corneal flap and the corneal 8troma started at day 7 postoperatively and peaked at 1 months and decreaaed around the corneal flap and the corneal 8troma started at day 7 postoperatively and peaked at 1 months and decreaaed t3mnh.TFβep( SBK:t=2.226,2.158,2.330,P＜0.05;PRK:t=4.745,6.524,6.293,P＜O.05).The numbers of activ( SBK:t=2.226,2.158,2.330,P＜O.05;PRK:t=4.745,6.524,6.293,P＜0.05).The numbers of activated MFs were different from LASIK statistically too between SBK group and PRK group ( SBK:t =4.439.5.692,4.175,P＜0.05 ; PRK:t=6.330,6.723,5.267,P＜0.05 ).The α-SMA and TCF-β expressions in SBK group were less than PRK group but more than LASIK group ( TCF-β:t =4.691,5.527,t =4.399,P＜0.05 ; α-SMA:t =9.637.10.282,8.197,P＜0.05).The numhers of MFs in SBK group was less than PRK group before 3 months and were same at 3 months ( t =5.188,4.529,P＜0.05 ).Conclusions Compared with conventional LASIK,SBK can up-regulate the expression of α-SMA.TGF-β,activated MFs in the corneal flap.which enhance corneal biomechanics and promote healing.However,most of the disadvantages caused by wound healing in SBK still remain compared to PRK. Key words: Sub-Bowmans keratomileusis; Myofibroblast; α-Smooth muscle actin; Transforming growth factor-β