The Short-term Effect Of Corneal Collagen Crosslinking Combined With SBK In The Treatment Of Middle And High Myopia

Research background and objective:Background: myopia is a kind of public health problem that seriously endangers people’s health in China.With the popularization of electronic products and the education system and other factors in China,the number of people with myopia is increasing.Excimer laser surgery is the most advanced technology in the treatment of myopia at present.Femtosecond laser keratorefractive surgery and Laser-assisted in situ keratomileusis(LASIK)are the main methods of keratorefractive surgery at present.Because of the rapid recovery of corneal sensation after SBK,the incidence of dry eye is lower than LASIK.Therefore,SBK was selected for routine refractive surgery in our hospital.No matter what kind of excimer operation,the complications of iatrogenic corneal dilation can not be ignored,especially for the myopia with thin cornea and high degree.It is reported that uva-cxl can increase corneal hardness,maintain corneal mechanical stability,control the incidence of postoperative complications such as iatrogenic corneal dilation,and to a certain extent relax the diopter of surgery.Objective: To observe the short-term effect of UVA-CXL combined with SBK in the treatment of middle and high myopia.Materials and methods:Selected cases: 22 cases(41 eyes)of high myopia or myopia with thin cornea were selected.All patients voluntarily chose ultraviolet / riboflavin corneal collagen crosslinking(UVA-CXL)combined with laser keratomileusis under anterior elastic layer.All patients were examined for naked vision,best corrected vision,slit lamp anterior segment,corneal topography,corneal endothelioscope,intraocular pressure and fundus.Especially pay attention to corrected vision,optometry,corneal thickness,corneal endothelioscopy and corneal topography,and select qualified patients for operation.Methods: The eyes were washed with povidone iodine solution before operation.After anesthesia,SBK lamellar scalpel(corneal flap with thickness of 90 μ m,diameter of 8.5 mm and side cutting angle of 90 °)was used.According to the results of optometry calculation before operation,American V4 excimer laser was used to cut the cornea;the corneal flap was restored;after the corneal flap was restored,it was cross-linked via epithelial cornea,vibex Xtra riboflavin solution was used to cover the corneal flap(120s).Ultraviolet light(KXL system)with wavelength of 370 nm and illumination of 30 MW / cm2 was used to irradiate the cornea for 90-120 s.The total energy of irradiation was 2.7j/cm2.After the operation,dianbishu eye drops should be taken immediately.After the operation,flumilong eye drops and sodium hyaluronate eye drops should be taken.The best naked visual acuity(UCVA)and corneal topography,intraocular pressure,corneal endothelioscopy were observed 1 day,1 W,1 m,3 m,6 m,1 y after operation.Result:1.Postoperative visual acuity: compared with the expected visual acuity before operation,the best visual acuity(73%)could not be achieved on the first day after operation.Within 1 week,all patients achieved or exceeded the best corrected visual acuity before operation.At 1,3 and 6 months after the operation,the UCVA of all eyes was improved,and the best corrected visual acuity was achieved or exceeded within 1 year after the operation(P < 0.05).No refractive regression,corneal dilation and other complications were found.2.Corneal topography: on the first day,1,3,6 and 12 months after operation,the corneal curvature was stable and the corneal topography was smooth.Among them,the SAL increased first and then decreased,the Sim K difference and Sim K equivalent value were lower than those before operation.Although the Sri increased first and then decreased,it was lower than that before operation There was no significant difference between 1,3,6,12 months after operation.3.Corneal endothelial cell count: the average was 2724.33/mm2 before operation,2662.77/mm2,2669.08/mm2,2680.91/mm2,2706.33/mm2,2694.27/mm2 at 1 week,1 month,3 months,6 months and 12 months after operation,respectively.There was no significant difference between the preoperative and postoperative time points.Therefore,uva-cxl combined with laser keratomileusis has no significant effect on corneal endothelium.Conclusion:1.Ultraviolet / riboflavin corneal collagen crosslinking combined with laser keratomileusis under anterior elastic layer is as effective and safe as SBK alone.2.The biomechanical stability of cornea after Ultraviolet / riboflavin corneal collagen crosslinking combined with laser keratomileusis under anterior elastic layer is better.Although the vision recovery of patients after this operation is not as good as that of SBK operation alone in a short time,it expands the indication of operation under the condition of ensuring the biomechanical safety of cornea.3.Ultraviolet / riboflavin corneal collagen crosslinking combined with laser keratomileusis under the anterior elastic layer can effectively reduce the incidence of corneal dilation,corneal swelling and other complications in the short term,and the long-term effect needs further observation.4.Ultraviolet / riboflavin corneal collagen cross-linking combined with laser keratomileusis under the anterior elastic layer is stable in the short term,without refractive regression,and the long-term effect needs further observation.