Excimer laser keratomileusis is a computer-controlled, non-invasive refractive eye surgery. The laser beam precisely cuts a certain thickness of the cornea to change the refractive power of the corneal surface for the purpose of correcting myopia, hyperopia and astigmatism. After these 40 years of clinical treatment observation, it is found that the following types of excimer laser surgery are used clinically: 1. PRK (excimer laser refractive keratomileusis) requires scraping the corneal epithelium and laser cutting during surgery. For medium and low myopia (below 600 degrees) the treatment effect is good and stable, but for high myopia, the effect is poor. The reason for this is that PRK surgery removes the corneal epithelium and the anterior elastic layer, and the cutting depth is deeper for high myopia, resulting in corneal foggy clouding during the corneal epithelial repair process, causing a decrease in corneal transparency and regression of myopia correction results. 2, LASIK surgery (laser in situ keratomileusis) is based on PRK, the main process is to make a flap on the superficial surface of the cornea with a manual or automatic corneal lamellar cutter, lift the flap and then hit the laser, then reset the flap (without sutures). This preserves the integrity of the corneal epithelium and the anterior elastic layer, eliminating the source of postoperative corneal haze clouding. Thus, the main advantages of LASIK surgery over PRK surgery are a wider range of treatment indications (up to 1400 degrees of myopia), more stable results, less chance of postoperative infection, and a painless, rapid recovery with a short postoperative medication schedule. However, the surgical skills required are relatively high, and certain additional equipment is needed. 3.LASEK/Epi-LASIK (excimer laser epithelial flap submounting) is a procedure that uses a specially designed corneal epithelial knife to create an epithelial flap. It is more precise than PRK surgery and produces a flatter epithelial flap with significantly less postoperative pain, rapid recovery of effective vision, lighter regression, significantly less Haze, and greater safety assurance. The difference with LASIK is that the epithelial flap thickness is only 60~80 microns, so it is an option for patients with a high number and thin corneal thickness who cannot perform LASIK. Patients need to wear corneal contact lenses for 3~7 days after surgery to prevent the ultra-thin epithelial flap from shifting, and the postoperative pain is slightly stronger than LASIK. 4, SBK surgery (anterior subelastic keratomileusis) is a more advanced surgery than LASIK surgery, with better quality of flap production, less biomechanical impact on the cornea, and lower incidence of post-operative dry eye symptoms. 5.Femtosecond laser-assisted LASIK/SBK: Femtosecond laser is used instead of keratome to make corneal flap, and then excimer laser is used to make refractive resection of corneal stroma to correct refractive error. Advantages: it can avoid the complications associated with the keratome and improve the safety of the surgery; the parameters of the flap are very precise and reduce complications; the incidence of dry eye is low and the recovery is fast after surgery. 6, individualized keratomileusis In recent years, with the development of the times, according to the individual differences or needs of patients, “tailor-made” type of targeted surgical design, and then the implementation of surgery, the concept of individualized surgery is more and more patients and physicians requested and respected. (1) Topography-guided individualized cutting (T-CAT) provides an effective surgical approach for patients with refractive errors that cannot be corrected by traditional refractive surgery (e.g., irregular corneas, especially those caused by trauma, corneal disease, or irregular astigmatism after keratoconus surgery). It first measures the irregular cornea with a corneal topographer to obtain corneal topography and refractive information, which is then converted to a flypoint scanning excimer laser machine and processed by relevant software to obtain an individualized cutting procedure to change the irregularities in the corneal morphology to a smooth and regular morphology, thus correcting the refractive error. Indications for surgery: refractive error, especially irregular corneal astigmatism caused by various reasons, such as: correction of off-center after PRK and LASIK; larger central island; those who are not suitable for wavefront aberration-guided individualized cutting due to clouding of refractive media such as lens or vitreous; corneal aberrations caused by corneal replacement or ocular trauma; corneal aberrations caused by implantation of artificial lens. (2) Wavefront aberration-guided individualized surgery (A-CAT): Traditional refractive surgery causes an increase in higher-order aberrations while correcting lower-order aberrations, which is the main reason for the decrease in visual quality of patients after refractive surgery, causing a decrease in contrast sensitivity, night vision, halos, glare, etc. The combination of wavefront aberration theory and refractive surgery, resulting in wavefront aberration-guided individualized cutting, is currently the most respected way to solve this problem. After the wavefront aberrometer measures the aberration of the eye, the aberration is connected to the excimer laser, and the aberration is used as the main parameter of the surgery, and mathematical modeling is performed to convert the aberration into cutting volume. The aim is to focus every point projected to the cornea accurately at the macula so that the laser-corrected human eye image is ideal. Wavefront aberration-guided individualized cutting can significantly reduce the increase of higher order aberrations after traditional refractive surgery, thus improving visual quality. (3) Q-adjusted individualized cutting surgery (F-CAT): Through corneal topography, corneal information is processed by Q-adjustment software to obtain the Q-value of the operated eye. The Q value of the operated eye is obtained, and the target Q value in the postoperative corneal optical zone (OZ) is set, and the information and energy conversion of the laser cutting machine enables the refractive power distribution of the cornea in the OZ to maintain or be close to the physiological characteristics of high central refractive power and relatively low peripheral refractive power before surgery while correcting refractive error, which is conducive to focusing the light entering the eye at one point although it is in different off-axis positions and can effectively reduce the spherical aberration introduced by refractive surgery. It can effectively reduce the spherical aberration introduced by refractive surgery and correct the original spherical aberration of the cornea through surgery. Indications for surgery: dark light or large pupil at night; small preoperative high-order aberration, good corrected visual acuity; medium and high myopia; special requirements for dark vision. 7.T-PRK surgery: The difference between T-PRK and PRK is that T-PRK uses laser to remove the corneal epithelium and corneal stroma, and all the excimer laser to complete the cutting of myopic refraction. The procedure is faster, safer and blade-free. The disadvantages are similar to PRK. Like other refractive surgery procedures, excimer laser surgery is only suitable for adults, generally requiring patients to be 18-55 years old and free of serious eye disease and systemic illness. Before surgery, patients must go to the hospital for a comprehensive eye examination. For those who wear soft contact lenses, the lenses must be removed for more than one week before the examination and surgery, and for those who wear hard contact lenses, the lenses must be removed for more than one month to avoid affecting the examination and surgery results. Laser surgery can be done on both eyes at the same time and takes about 10~15 minutes. On the day of surgery, you will need to wear an eye patch, and you do not need to be hospitalized. The next day, you will remove it when you go to the hospital for examination, and then you will start to order eye medication and maintain it for three to four weeks. Generally, you can go to work three days after the surgery, but you must read less books, newspapers and TV within a week to avoid eye fatigue. As long as the thickness of the cornea retained after surgery is sufficient, laser surgery will not change the ability of the cornea to resist external forces, and ordinary external forces and air pressure will not cause danger. However, you should not rub your eyes or swim for one month after surgery to avoid dislocation of the corneal flap. If a foreign body enters the eye and the eye medication does not work, you should go to the hospital for treatment. ———- ———- ———- ———- — Special Note: 1. Laser surgery is only suitable for adults, requiring patients to be 18-55 years old and free of serious eye diseases and systemic diseases. 2. Before laser surgery, patients must go to the hospital for a comprehensive and systematic eye examination. For those who wear soft contact lenses, they should take off their lenses for more than one week before the examination and surgery, and for those who wear hard contact lenses, they should take off their lenses for more than one month to avoid affecting the examination and surgery results. 3. In principle, laser surgery can be performed on both eyes at the same time. Hospitalization is not necessary. 4. In general, you can go to work three days after the surgery, but you must read less books, newspapers and TV within a week to avoid eye fatigue. Laser surgery does not change the ability of the cornea to resist external forces, and ordinary external forces and air pressure do not cause danger. However, you should not rub your eyes with force for one month after surgery, and you should not swim for six months. If a foreign body enters the eye and the eye drops do not work, you will need to go to the hospital for treatment.