Since I have seen some people say that laser surgery is a cosmetic surgery, and say it three times to show its importance, let me introduce what this so-called "cosmetic" surgery is.

This surgery is called excimer laser surgery, or LASIK in English. The principle of LASIK surgery is not complicated. Myopia is caused by the eyeball's front and rear axis being too long or the eyeball's refractive index being too high. The focus of the image falls in front of the retina, making distant objects blurry. By changing the refractive index of the eyeball so that the focus falls on the retina, myopia is corrected. When performing laser correction surgery, the cornea must first be cut and circumferentially cut 330 degrees to create a corneal flap, and then the corneal flap is lifted to expose the underlying corneal stroma. This is when the laser comes in handy, aiming at the corneal stroma to evaporate part of the stromal tissue, thinning the stroma, and changing the curvature of the cornea. How much substrate is evaporated is calculated by a computer and can be precisely controlled. The corneal flap is then covered and the surgery is complete.

The biggest problem with LASIK surgery is corneal circumcision. There are abundant sensory nerves on the cornea, so we can feel foreign objects in the eyes, "there is no room for sand in the eyes", and secrete tears immediately as needed to moisten the eyes and prevent them from drying out. LASIK requires circumcision of the cornea, and the nerves on the cornea are severed. The cornea cannot sense changes in the outside world normally, and the reflex mechanism of tear secretion is affected, making the eyes prone to dryness. So the most common complication of LASIK surgery is dry eye. Dry eyes can affect vision. One of the functions of keeping the eyeball moist is to make the cornea smooth, so that the image will be clear. On the contrary, dry eye will make the cornea not smooth, and the clarity of the eye image will be affected. Even with the most successful LASIK surgeries, the clarity of vision after surgery is a little less than with glasses (including contact lenses). If dry eye is severe, it will cause premature death and shedding of corneal epithelial cells, making the corneal surface uneven and causing astigmatism, ghosting, and foggy vision. The corneal nerves will gradually grow back after surgery, but less than 50% of the corneal nerves grow back three years after surgery. Unless the nerves return to their pre-surgery state, dry eye may become permanent.

Dry eye syndrome requires frequent use of eye drops to moisten the cornea so that the image can be clear, which is really troublesome. But it has advantages over wearing contact lenses. According to a 2006 report published in the Archives of Ophthalmology, people who wear contact lenses every day have a 1% chance of developing a serious eye infection within 30 years and a 2‰ chance of severe vision loss due to infection. The risk of severe vision loss from LASIK is 1 in 10,000. From this perspective, wearing contact lenses is actually less safe than having LASIK surgery. The safest option is of course to wear regular glasses, at the expense of inconvenience.

The recommendation of the Mayo Clinic in the United States (one of the best hospitals in the United States) is that if you have a disease that affects wound healing (such as rheumatoid arthritis, lupus, AIDS), and are taking immunosuppressive drugs , suffer from persistent dry eye syndrome, cornea that is too thin or the corneal surface is irregular, pupils that are too large, eyelid position is abnormal, glaucoma, unstable vision, pregnancy or breastfeeding, etc., will increase the risk of complications and may not be suitable Have LASIK surgery. You should also carefully consider whether to have LASIK surgery if you have the following situations: If you are highly myopic, the risks of surgery may outweigh the benefits; if your vision is already quite good and you only need to wear glasses occasionally, then the limited improvement you can get through surgery may not be worth the risk. Risks: Regular participation in contact sports may result in frequent hits to the face or eyes.

All surgical decisions must be made after weighing the pros and cons, especially for unnecessary surgery such as the correction of myopia. You should be more cautious.

Additional point: Myopia is determined by the myopia gene. Only the amount of sun exposure can have some impact on the expression of the myopia gene. Other uses of the eyes include reading (including under dim lights) and looking at electronic screens. (Including the smallest and brightest mobile phone screen) etc. will not cause people without myopia genes to develop myopia. People with the myopia gene will also develop myopia if they don't read books or watch electronic screens.