1, if conjunctivitis, blepharitis and severe trachoma must be cured before operation; If there is inflammation around the eyes, suspend the operation; Drop antibiotic eye drops one day before operation, twice a day;

2. Subjects with a history of bleeding tendency should check platelets and clotting time;

3, middle-aged and elderly patients need to measure blood pressure and electrocardiogram when necessary, if there are mild abnormalities, preoperative medication should be symptomatic;

4. Avoid the menstrual period for surgery;

5. Suspension of surgery in the first trimester (three months) or the third trimester (three months);

6, 7- 10 days before surgery, stop using anticoagulant drugs such as steroid hormones and aspirin;

7. Scar constitution is prohibited.