Patient: Hello doctor I would like to have myopia surgery but after reading an article on the internet I have some doubts and I hope you can help me with the following questions 1. However, since LASIK cuts the corneal tissue, the cut corneal tissue cannot withstand the pressure of intraocular pressure on the cornea, so the cornea will gradually become sharp and eventually form a cone. 2. Some hospitals believe that retaining 410 is the bottom line of safety, what is the basis for this? Who can guarantee that people with corneal thickness at the lower end of the range will not have their corneas gradually deformed over a period of 10 years or so and develop cone corneas? And which ophthalmology authority can come forward to guarantee that those who need to cut more corneal tissue due to high myopia (600 degrees or more) will not have problems in 15 or 20 years? I am curious to know why some ophthalmologists who wear glasses do not perform myopia surgery. Doctor: Thank you for your interest in the principles of myopia surgery. You have a good question, and you can also refer to some scientific articles that I and other doctors have written. Cone keratoconus is a corneal disease with a genetic predisposition and is related to the biomechanics of the cornea. Based on normal IOP results (10-21 mmHg), the average cornea can resist this pressure without deformation. However, corneal thickness is not the most important factor; a more important factor is the strength of the corneal tissue fibers. In other words, corneal thickness and conical cornea are not corresponding positive relationship. 1, Before LASIK, detailed examination and evaluation is the key to prevent postoperative cone cornea. The formation of postoperative cone corneas, about 90%, is due to the preoperative failure to detect preclinical cone corneas; 2, the description of 410 microns is not quite correct, for LASIK, the main concern is whether the thickness under the corneal flap is above 250 microns, and of course the more is retained the safer. However, it is not absolute, but also related to the strength of the corneal fibers and their own IOP as mentioned earlier. Excimer laser surgery for myopia has been performed for more than 20 years since its inception, and from a worldwide perspective, the vast majority of these patients who have had the surgery have not been observed to have cone corneal changes to date (provided of course that the safe thickness is preserved). As for the last question, I have answered it many times before: myopia surgery is an elective procedure, similar to “cosmetic surgery”, and not everyone wants to do it. Of course, there are many ophthalmologists and their families who have undergone this type of surgery.