China is one of the countries where laser keratomileusis is most widely performed. In order to further standardize the clinical application of laser keratomileusis and ensure medical quality and safety, expert members of the Cornea Section of the Ophthalmology Branch of the Chinese Medical Association have reached the following consensus, taking into account the actual situation in China. Laser keratomileusis is usually divided into the following two categories: laser lamellar keratomileusis and laser superficial keratomileusis. Laser lamellar keratomileusis Laser lamellar keratomileusis usually refers to excimer laser in situ keratomileusis (LASIK), which is the mainstream laser keratomileusis procedure, and also includes the procedure of completing the corneal stromal microlens and removing it by femtosecond laser only. (A) Indications 1, the patient has the desire to remove the lens and has reasonable expectations of the surgical results. 2, age ≥ 18 years old (except for special circumstances, such as career requirements, high refractive index, corneal disease requiring laser treatment, etc.); pre-surgery on the basis of full understanding of the patient and his family must sign the informed consent. 3.The refractive status is basically stable (myopic refractive error growth is not more than 0.50 D per year) for ≥ 2 years. 4, refractive error: myopia ≤ -12.00 D, astigmatism ≤ 6.00 D, hyperopia ≤ +6.00 D. For those who use only femtosecond laser to complete the corneal stromal microlens and remove the procedure, it is recommended that the sum of the corrected refractive error of spherical lens and column lens ≤ -10.00 D. The range of refractive error correction with various laser devices should be within the range approved by the China Food and Drug Administration. (B) Contraindications 1, absolute contraindications (1) suspected cone cornea, diagnosed cone cornea or other types of corneal dilatation. (2) Active inflammatory reaction and infection of the eye. (3) Corneal thickness cannot meet the set cutting depth: central corneal thickness <450 μm, expected central corneal stromal thickness <250 μm under the flap after cutting (280 μm recommended), expected central corneal stromal thickness remaining after surgery is less than 50% of the preoperative corneal thickness. (4) Severe dry eye. (5) Severe ocular appendage pathology: e.g., eyelid defect, deformity, etc. (6) Uncontrolled glaucoma. (7) Cataracts affecting vision. (8) Uncontrolled systemic connective tissue diseases and autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. (9) Anxiety, depression and other psychiatric symptoms. 2. Relative contraindications (1) The contralateral eye is legally blind. (2) Ultra-high myopia combined with significant posterior scleral staphyloma and corrected visual acuity <0.3. (3) Mild lid closure insufficiency. (4) Abnormal orbital, eyelid or ocular anatomy that prevents the microkeratome or femtosecond laser from working properly. (5) Excessive corneal steepness (corneal curvature >47 D) or excessive flatness (corneal curvature <38 D). (6) Unstable refractive status with a change in refractive error of 1.00 D or less every 2 years. (7) Poor corneal epithelial adhesion, such as epithelial basement membrane dystrophy, recurrent corneal epithelial erosion, etc. (8) Corneal stromal or endothelial dystrophy. (9) Moderate dry eye. (10) Pupil diameter greater than the planned corneal cutting diameter in dark illumination. (11) History of herpes simplex virus keratitis. (12) History of retinal detachment and macular hemorrhage. (13) Diabetes mellitus. (14) Glaucoma (well-controlled intraocular pressure). (15) History of connective tissue disease, autoimmune disease. (16) Pregnant and lactating women. (17) Those who are at high risk of corneal trauma. (18) Taking certain systemic medications such as glucocorticoids, estrogens, progestins, immunosuppressants, antidepressants (isotretinoin, amiodarone, levonorgestrel implants, colchicine, etc.), etc. (19) Age <18 years old. (20) Excessive expectations for surgery. < span=""> (C) Preoperative evaluation A thorough medical history and ocular evaluation should be performed prior to all types of laser keratomileusis. 1. Medical history: In addition to the medical history of systemic and ocular diseases, the reasons for surgery (e.g., lens removal, discomfort with lenses, schooling, employment, etc.) and the stability of refractive status in the past 2 years should be understood. Corneal contact lens wearers should stop using them until the refractive status and corneal curvature reach a stable state: spherical soft lenses should stop wearing them for 1 to 2 weeks, astigmatic soft lenses and rigid gas permeable corneal contact lenses should stop wearing them for 3 to 4 weeks, and keratoplasty lenses should stop wearing them for more than 3 months. 2. Routine eye examination (1) Visual acuity: monocular and binocular naked vision, small-aperture visual acuity, near vision and customary corrected visual acuity (visual acuity with lenses). (2) Eye position and eye movements: presence of occult strabismus or strabismus. (3) Objective optometry: computerized optometry and shadowing optometry for initial measurement of refractive status under the small pupil. (4) Comprehensive optometry: determine the refractive state under the small pupil according to the principle of maximum plus to maximum visual acuity (MPMVA), and give frame glasses or corneal contact lenses for trial wear if necessary. Patients with ciliary muscle paralysis should wait for the pupil to return to normal before re-testing. (5) Determine the dominant eye. (6) Check the corneal topography. (7) Use slit lamp examination method (before dilating the pupil) to rule out anterior segment disease (8) Test IOP: screen patients with hypertensive eye disease and glaucoma with a flattened or non-contact tonometer. (9) Measure pupil diameter: measure pupil diameter in bright and dark vision (10) Use slit lamp examination method (after dilating the pupil) to further exclude anterior segment and anterior vitreous disease. (11) Use direct and indirect fundoscopy to rule out posterior segment disease, and perform trifocals if necessary. (12) Measurement of corneal thickness: determine the central corneal thickness and, if necessary, the paracentral corneal thickness. 3.Special examination items: According to the patient’s complaints and symptoms and the findings during routine examination, take the following examinations if necessary. (1) Tear test: tear film break-up time (BUT), tear secretion test (Schirmer test). (2)Corneal morphological examination: analysis of corneal wavefront aberration, anterior and posterior corneal surface and corneal thickness. (3) Ocular visual quality examination such as whole-eye wavefront aberration. (4)Contrast sensitivity and glare examination. (5)A ultrasound examination: to determine whether the refractive error degree is consistent with the eye axis length. (6) Adjustment and vergence function examination. (4) Informed consent 1. It is the surgeon’s responsibility to obtain the patient’s informed consent. 2. The patient should be informed preoperatively of the potential risks, benefits, alternative treatments, and differences between refractive procedures. 3. Detailed information to the patient should include the expected postoperative refractive status, the possibility of residual refractive error, the continued need for correction in reading and/or distance vision, the possibility of reduced best-corrected visual acuity, changes in visual function (e.g., glare and visual dysfunction in dark environments), the risk of infectious keratitis, the possibility of secondary corneal dilatation, the possibility of adverse drug reactions or other complications possible. 4. Patients should be informed of the possibility of short-term postoperative dry eye symptoms or the possibility of progression or worsening of dry eye symptoms. 5. The advantages and disadvantages of monocular vision should be discussed with patients who have reached the age of presbyopia. 6. The informed consent process should be documented so that the patient has the opportunity to have all questions answered prior to surgery. (E) Perioperative management 1. Preoperative medication (1) Broad-spectrum antibiotic drops for 3 d, 4 times a day; or 2 d, 6 times a day; or 1 d, frequently. (2) If the cornea is defective in the punctate epithelium, artificial tears or corneal epithelial repair drugs can be used until the cornea heals. (3) If there are dry eye symptoms, artificial tears can be used as appropriate. 2.Surgical method (1)Routinely clean the conjunctival sac before surgery, or choose tear duct flushing for special patients. (2) Confirm the accuracy of the parameters of the patient, the operated eye, and the input to the excimer laser computer. (3) Cover the non-operative eye, anesthetize the operative eye, and place a lid opener to expose as much of the cornea as possible. (4) It is recommended that the cornea be marked to facilitate resetting the flap at the end of the procedure. (5) If a microkeratome is used to create the flap, a negative pressure suction ring matching the curvature of the cornea must be placed on the cornea to confirm that effective suction is achieved, and then a corneal flap with a tip is created with the microkeratome. The tip can be created in different positions using different microkeratomes. The working condition of the microkeratome and the condition of the blade should be carefully checked before operation. (6) If a femtosecond laser is used to create a corneal flap or corneal stromal lens, a corneal suction ring of appropriate diameter should be selected, the eye should be fixed with negative pressure, the laser separation depth should be set, and then laser flap creation or corneal stromal lens creation should be performed. (7) The corneal flap is examined and then lifted and reflexed, and the size and regularity of the corneal flap and stromal bed are carefully examined. (8) If the corneal flap and stromal bed are of sufficient quality, excimer laser cutting can be performed. If the corneal stroma is not adequately exposed or the stromal bed or flap is irregular, it is recommended to stop excimer laser cutting and flatten the flap in situ. 1 to 3 months after the flap has healed, consider performing superficial or lamellar surgery again. (9) Excimer laser cutting is performed on the corneal stromal bed with the corneal apex or visual center as the center, and the cutting center needs to be adjusted and shifted if necessary. (10) After excimer laser cutting, the corneal flap is reset, the interface between the flap and the stromal bed is rinsed thoroughly with balanced saline, the flap is smoothed with a chipless absorbent sponge, and good alignment of the flap is confirmed. (11) Confirm that the corneal flap is attached, and then remove the lid opener. (12) If a corneal stromal microlens extraction procedure is performed, i.e., femtosecond laser small incision lenticuleextraction (SMILE), an incision of 2 to 4 mm in length can be separated at the corneal cap margin, and after adequate blunt separation above and below the corneal stromal lens, the corneal stromal lens is removed intact, rinsed, and then smoothed with a After rinsing, the corneal cap was smoothed with a non-chip absorbent sponge. (13) Apply topical broad-spectrum antibiotics and glucocorticoid drops. (14) Before the patient leaves, the operated eye should be re-examined using slit lamp examination to confirm that the position and appearance of the corneal flap are not abnormal. If the tracking is not available during the surgery, the tracking can be canceled and excimer laser cutting can be performed according to the positioning of the corneal apex. 3, postoperative medication and treatment (1) postoperative transparent eye shield for eye protection. (2) Antibiotic drops for 7~14 d. (3) Glucocorticoids or new non-steroidal anti-inflammatory drops for 1~2 weeks, and decreasing as appropriate. (4) Artificial tears or gel eye drops. ( 5) Regular post-operative review is required, which usually takes place on the first day, 1 week, 1 month, 3 months, 6 months and 1 year after surgery. 4, augmentation surgery or re-operation (1) lamellar surgery: for undercorrection and overcorrection of refractive error after lamellar surgery, the conditions allow for correction by re-operation. The timing of reoperation is usually better when the corneal condition is good and the refractive state is basically stable 1~3 months after the initial surgery. In general, if the flap is normal and the remaining stroma is sufficient, the flap can be lifted directly; if the flap is too thin or irregular, the flap can be recreated or converted to a superficial surgical approach as well as using corneal topography or wavefront aberration to guide the surgery. (2) Augmentation surgery after radial keratotomy (RK) should be performed with caution, and augmentation surgery should be performed at least 2 years after RK, and LASIK is recommended. (3) Superficial surgery: laminar surgery after superficial surgery should be performed at least 1 year after surgery. (F) Postoperative adverse reactions and complications 1. Optical adverse reactions and complications (1) Undercorrection or overcorrection of the refractive error with symptoms. (2) Refractive status regression. (3) Loss of best corrected visual acuity. (4) Visual disturbances, including transient or permanent glare or halos, especially at night with loss of vision. (5) Decreased contrast sensitivity. (6) Development of regular or irregular astigmatism. (7) Development of refractive aberrations. (8) Premature need for reading glasses. 2, medical adverse reactions and complications adverse reactions: (1) non-infectious diffuse interlaminar keratitis, also known as interlaminar Sahara reaction of the corneal plate. (2) Dry eye symptoms or worsening of existing dry eye symptoms. (3) Decreased corneal perception. (4) Recurrent corneal erosion. (5) Recurrence of herpes simplex virus keratitis. (6) Early or delayed onset of corneal haze (haze) and scarring. Complications: (1) Corneal flap complications, such as free flap, small flap, shattered flap, button flap and incomplete flap; corneal epithelial implantation. (2) Gas entry into the anterior chamber. (3) Corneal infiltration, ulceration, melting, or perforation (aseptic or infectious). (4) Glucocorticoid-induced complications, such as hypertension, glaucoma, cataract. (5) Corneal dilatation or secondary cone corneas. (6) Posterior segment lesions, such as retinal fissures or detachments. Second, laser superficial keratomileusis Laser superficial keratomileusis refers to the removal of corneal epithelium by mechanical, chemical or laser means, or mechanical fabrication of corneal epithelial flap followed by laser cutting on the surface of the anterior elastic layer of the cornea and its underlying corneal stroma, including: excimer laser refractive keratomileusis (photorefractive keratectomy, PRK) Laser subepithelial keratomileusis (LASEK), epipolis-laser in situ keratomileusis (Epi-LASIK), and trans-epithelial excimer laser keratomileusis (Trans-EASEK). Trans-Epithelial photorefractive keratectomy (TPRK). (A) Indications 1, basically the same as lamellar surgery, the recommended refractive error ≤-8.00 D. 2, special occupational needs, such as more confrontational athletes, armed police, etc. 3. Special anatomical conditions such as thin corneas, small lid fissures, and deep sockets are not easy to perform lamellar surgery. 4.The remaining stroma is expected to be too thin for augmentation surgery, while the corneal flap thickness is sufficient. 5, The patient requests or the physician recommends surface cutting. 6, superficial corneal disease accompanied by refractive error. (B) Contraindications 1, absolute contraindications are basically the same as LASIK. 2, relative contraindications (1) The contralateral eye is legally blind. (2) High myopia with significant posterior scleral staphyloma and corrected visual acuity <0.3. (3) Mild lid closure insufficiency. (4) Corneal stromal or endothelial dystrophy (corneal endothelial cell count >1,500 cells/mm2). (5) Corneal topography suggestive of abnormalities, such as strobic cone corneas or other types of corneal dilatation (corneal scarring after corneal trauma, after corneal transplantation, etc.). (6) Moderate dry eye. (7) Pupil diameter greater than the planned corneal cutting diameter under dark illumination. (8) History of herpes simplex virus keratitis. (9) Diabetes mellitus. (10) Glaucoma (well-controlled intraocular pressure). (11) History of connective tissue disease, autoimmune disease. (12) Taking certain systemic medications, such as glucocorticoids, estrogens, progestins, immunosuppressants, antidepressants (isotretinoin, amiodarone, levonorgestrel implants, colchicine, etc.), etc. (13) Pregnant and lactating women. (14) Age < 18 years. < span=""> (iii) Preoperative evaluation Basically the same as LASIK. (iv) Informed consent Basically the same as LASIK. patients should be informed that they are more prone to postoperative haze, high intraocular pressure, fluctuating refractive status; that the recovery time of visual acuity is relatively long; that they need to follow up regularly and avoid direct ocular ultraviolet radiation, etc. (E) Perioperative treatment 1, preoperative medication (1) basically the same as LASIK. (2) can be used as appropriate new non-steroidal anti-inflammatory drugs, it is recommended that 30, 15 and 5 min before surgery, each time to reduce the postoperative pain response. 2.Surgical method (1)Routinely clean the conjunctival sac before surgery, or choose tear duct flushing for special patients. (2) Confirm the accuracy of the parameters of the patient, the operated eye, and the input to the excimer laser computer. (3) The operative eye is anesthetized and a lid opener is placed to expose the cornea. (4) Remove the corneal epithelium with a scraper (PRK), microkeratome (debulking Epi-LASIK), or laser (TPRK), or create a corneal epithelial flap with a microkeratome (Epi-LASIK) or 20% ethanol treatment followed by a ring drill and scraper (LASEK). (5) The extent of exposed corneal stroma should be sufficient to include the planned excimer laser cut. (6) Excimer laser cutting of the anterior corneal elastic layer and stroma is performed with the corneal apex or visual center, and the center of the cut needs to be adjusted for displacement if necessary. (7) Excimer laser cutting is followed by adequate rinsing with cold balanced saline. (8) Excimer laser cutting to a greater depth may be used with caution with 0.02% mitomycin C. (9) The epithelial flap with corneal epithelium should be repositioned and the epithelial flap smoothed into approximate alignment with a chipless aspirating sponge or removed directly. (10) Routine topical spotting of antibiotics, glucocorticoids, and newer NSAIDs. (11) Use a bandage contact lens. (12) Remove the lid opener. 3. Postoperative medication and treatment (1) Wear bandage contact lenses for several days (3-5 d) until the corneal epithelium has recovered. (2) Corneal epithelial growth drops can be added to help the corneal epithelium heal. (3) Pain relief tablets are reserved. (4) Antibiotic eye drops are ordered continuously for 7 d. (5) Glucocorticoid eye drops are ordered immediately after surgery and four times daily for 7-10 d. Depending on the patient’s myopia correction, degree of regression and haze, glucocorticoid eye drops are ordered continuously for 1 to 3 months, decreasing as appropriate according to the monthly decreasing principle. New non-steroidal anti-inflammatory drugs may also be chosen for patients with elevated intraocular pressure or easy loss of visit. (6) Monitor IOP at the same time. (7) Artificial tear spotting for several months. (8) Wearing sunglasses outside is recommended to prevent UV damage. (9) Regular postoperative review is required, usually on the 1st or 3rd day, 1 week, 1 month, 2 months, 3 months, 6 months, and 1 year after surgery. Special discomfort is reviewed at any time. 4, augmentation surgery and re-operation (1) After surface cutting due to refractive undercorrection, overcorrection or refractive status regression need to operate again, should be carried out after at least 6 months of stability of refractive status, haze and corneal topography examination after the initial surgery. (2) Those who have haze and need to be treated again should be seriously considered. grade 2 or more haze, affecting visual acuity preferred topical glucocorticoid spot eye, according to the situation increase the amount and time of glucocorticoid, 1 year application of glucocorticoid effect is not good can be considered for re-operation. During surgery, 0.02% mitomycin C can be used to prevent haze from reoccurring (choose carefully). (3) Superficial surgery after corneal transplantation: The refractive status is stable for more than 1 year after the removal of corneal transplantation. Those with poor corneal wound healing should avoid surgery. (F) Postoperative adverse reactions and complications 1. Optical adverse reactions and complications are basically the same as LASIK. 2. Medical adverse reactions and complications (1) Short-term postoperative pain and discomfort. (2)haze or scarring (early or delayed occurrence). (3) Complications caused by glucocorticoids, such as hypertension, glaucoma, cataract. (4) Delayed healing of corneal epithelium, filiform keratitis. The rest is basically the same as lamellar surgery.