1, if conjunctivitis, blepharitis and severe trachoma must be cured before operation, if there is inflammation around the eyes, suspend the operation and drop antibiotic eye drops one day before operation.

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

3. Middle-aged and elderly patients need to measure blood pressure and electrocardiogram when necessary. If there is slight abnormality, symptomatic medication should be taken before operation.

4, general examination, various laboratory tests, pay special attention to whether there is a tendency to bleeding, women avoid menstruation for surgery.

5. Stop using anticoagulant drugs such as steroid hormones and aspirin 7- 10 days before operation.