The Effectiveness of YAG Iridotomy in Preventing Peripheral Anterior Synechia After CLASS in Primary Open Angle Glaucoma

Inclusion Criteria: * Primary open angle glaucoma patients in Ophthalmic Center; * Topical use of hypotensive drugs in the treatment of poor or intolerable intraocular pressure control; * The patients were 18 to 50 years old, regardless of gender; * Class operation was performed; * Patients are able and willing to comply with the research guidance and may complete all visits required by the research; * Informed consent has been signed. Exclusion Criteria: * Allergic to any perioperative medication in this study; * History of ocular trauma; * Any previous intraocular surgery; * Gonioscopy showed a narrow angle (Schaffer III or below); * Secondary glaucoma was diagnosed; * Optic atrophy caused by other reasons; * Severe complications such as rupture of posterior capsule and choroidal hemorrhage occurred during operation; * Patients with severe ocular complications after operation * The patient's history indicated that he had severe dysfunction of heart, lung, liver and kidney; * Women in pregnancy, lactation or planned pregnancy; * The researchers believe that the patient's condition may put the patient at significant risk, may confuse the results of the study, or may significantly interfere with the patient's participation in the study.