You can’t judge the corneal thickness by yourself, you need to go to the hospital to do the relevant examination to determine the corneal thickness, the common examination methods are as follows: 1, A-type ultrasound corneal thickness gauge: only need to point anesthetic on the surface of the eye, after pointing the drug with the ultrasound probe on the cornea touch, you can detect the thickness of the cornea, has the characteristics of simple operation, high accuracy, the accuracy of measurement can reach 1 micron. 2, corneal topography: no contact with the eye, the operation is relatively simple and can be completed in about a few minutes, but the cost is higher than the A ultrasound examination. 3.Optical coherence tomography (OCT) measurement method: the accuracy of OCT is significantly better than ultrasound measurement method, and its resolution can reach 0.1 microns, but the cost is high. Measuring the thinness and thickness of the cornea is mainly used to determine the myopia surgery method. In determining the surgery method, it is first calculated based on the refractive error and corneal thickness, and then based on the patient’s age, occupation, sports habits, surgery purpose, eye habits and economic conditions, etc., the suitable surgery method is finally selected. In terms of safeguarding corneal safety, the stromal bed thickness after excimer laser lamellar keratomileusis must be greater than 280 microns, and the central corneal thickness after surgery should be greater than 400 microns. 1, excimer laser keratomileusis (LASIK) or semi-femtosecond (femtosecond-assisted LASIK) surgery This surgical procedure is performed by first cutting a corneal flap, which is thick or thin, with a flap thickness of about 90-120 microns, and cutting the required lens with an excimer laser under the flap. Number of degrees/100×12 microns. 2.Full femtosecond surgery (SMILE) Full femtosecond surgery does not have a corneal flap, but to make a lens, a convex lens needs to be removed directly in the center of the cornea, the upper layer of the lens is 90-120 microns thick, and a tiny incision (about 3 mm) has to be made in the periphery to remove the lens. Approximate cutting volume = degree/100×16+3. 3. Superficial surgery (PRK as an example) PRK is the earliest surgery, without making a corneal flap, first scraping off the epithelial layer (about 50 microns) in the central 8 mm diameter range of the cornea, and then laser cutting the cornea, which is one of the most corneal-saving surgical procedures. The depth of cut is approximately = the number of degrees/100 x 12 microns.