| Myopia is a kind of common ophthalmic disease. China is a nation of high - incidence of myopia, where the incidence of myopia is 50% and appears an increasing tendency year after year.The keratorefractive surgery has been developing from RK and PRK to LASIK and is becoming perfected gradually. LASIK combines the efficacy of excimer laser and the predominance that keratomileusis can keep the epithelium of cornea intact. The superiority of LASIK is that the procedure can keep the epithelium and Bowman membrane intact and postoperative recovery is rapid. Haze is scarce and the predictability of operation is high, which makes LASIK developed rapid-ly.Firstly, a 160 um - thick corneal flap is bladed by microkeratome and then photoablation under the corneal flap is performed. Therefore, it is the key of LASIK that preparation of corneal flap. There are corneal flap complications in some case, and free corneal flap is one of them. During preparation of corneal flap, if free corneal flap occurs and is large enough, photoablation can be performed and corneal flap can be replaced. The corneal flap with hinge can be replaced easily, but the reposition of free flap is difficult. Whether the reposition of free corneal flap can cause astigmatism has been put much emphasis on.Our experiment bladed free corneal flap on the rabbit cornea andobserved the postoperative change of cornea! astigmatism by cornea! topography in order to provide theoretical basis for clinic.Methods13 rabbits (26 eyes) were selected and divided into 2 groups randomly: experimental group(8 rabbits, 16 eyes) and control group (5 rabbits, 10 eyes). Before surgery, all of rabbits were examined by slit lamp microscope so as to exclude cornea! and ocular disease. The corneal astigmatism of all eyes was less than 1. 5D and the refractive power was between 42. OD and 45. OD.All of operations were performed by a doctor. Corneal Flap was bladed by Moria automated rotation microkeratome and 160 um - thick in the diameter of 9. 5 mm. General anesthesia was achieved with 846 muscle - injection (0. 3 ml /kg). Topical anesthesia was achieved with several drops of 0.4% beinuoxi. The eye was disinfected in routine , covered by a piece of scarf with a hole and anesthetized by topical drops. The eye was opened by blepharostat, and then alignment marks were placed on the cornea with methylene blue dye. In the experimental group, the No. 1 suction ring was positioned on the cornea, and a free flap was bladed by microkeratome when the negative pressure value of suction ring reached 180 mmHg. The free flap was replaced carefully according as the alignment mark and was rinsed with BBS solution. After the flap was dried in position for approximately 10 minutes, a drop of beifushu was placed on the eye and a eye patch was wore. In the control group, the No. 0 suction ring was positioned on the cornea, and a comeal flap with upper hinge was bladed by microkeratome when the negative pressure value of suction ring reached 180 mmHg. The flap was replaced and was rinsed with BBS solution. Af-ter the flap was dried in position, a drop of beifushu was placed on the eye and a eye patch was wore. During preparation of corneal flap, if the flap was incomplete we discarded it. The rabbits were sent back to animal room after operation. Tarivid eye drop was applied to the eye four times a day.The operated eye was examined by slit lamp microscope and corneal topography at 7 days, 2 weeks, 1 month, 2 months and 3 months after surgery and the state of cornea was recorded in order to analyze the change of corneal astigmatism and axis before surgery and after surgery in experimental group and control group. The data was analyzed by t - test dealt with SPSS10. 0 software.ResultsBy slit lamp microscope, we found that the corneal flaps were transparent or a little edema, the alignment of flaps was good, there wasnt epithelial ingrowth but round turbidity occurred on partial corne-a. There wasnt Haze on corneal optical area during following.The experimental... |
PDF Full Text Request