This is a 10-centre randomized controlled clinical trial to explore whether laser peripheral iridoplasty (LPIP) plus laser peripheral iridotomy (LPI) is more effective than single LPI to control the progression of primary angle closure with multi-mechanism based on the UBM classification.

Inclusion Criteria:

1. Clinical diagnosis of primary angle closure (PAC), with IOP≤30mmHg and PAS≤270°.
2. PAC with multi-mechanism based on UBM examination (multi-mechanism is defined as primary angle closure is caused by pupil block plus at least one kind of non-pupil block factors like (relative anterior position and thick of the ciliary body, the big volume of the iris, the anterior location of the iris insertion into the ciliary body)or any two or more kinds of combination.
3. Visual acuity≥ 20/40
4. Age between 40-75 years old Chinese people

If both eyes of a patient are eligible for the study, the e eye had worse visual acuity will be selected. Only one eye per patient is eligible for the study.

Drug washout:

Eligible patients who are already on anti-glaucoma medications are required to have drug washout before being randomized. Various medications have different washout periods: Prostaglandin analogues 4 weeks, Beta blockers 3 weeks, Adrenergic agonist 2 weeks, Cholinergic agonist 5 days, Carbonic Anhydrase Inhibitors 5 days. Patients whose IOP>30 mm Hg during this washout period will be stopped from further washout and be withdrawn from the study.

Exclusion Criteria:

1. Unwilling or unable to give consent, unwilling to accept randomization, or unable to return for scheduled protocol visits.
2. Angle closure due to secondary causes (subluxed lens, neovascular, uveitic, traumatic, post-operative)
3. Previous incisional intraocular surgery or ocular laser in study eye (LPI or LPIP, cyclodestructive procedure, cataract surgery)
4. Primary angle closure with glaucomatous neuropathy.
5. Have cataract in the studying eye and anticipated to have cataract surgery in the coming 3 years; the existing cataract affect visual field examination and fundus examination; the visual acuity <20/40 due to the existing cataract.
6. Who are using IOP lowing drugs and do not have drug washout
7. Need for glaucoma surgery combined with other ocular procedures (i.e. cataract surgery, penetrating keratoplasty, or retinal surgery) or anticipated need for urgent additional ocular surgery
8. Coexisting other ocular diseases (i.e. cornea abnormal or cornea infection, Iridocorneal endothelial syndrome or anterior segment dysgenesis, nanophthalmos, high myopia (>6.0D), Chronic or recurrent uveitis, ocular cancer, trauma, central retinal vein occlusion, central retinal artery occlusion, retinal detachment)
9. cornea endothelium counting <1000/mm2
10. need local or systemic steroid long-term use
11. Unwilling to discontinue contact lens use after surgery
12. Who are taking parting in other drug clinical trials
13. Pregnant or nursing women
14. Severe systemic disease (i.e. diabetes mellitus, hypertension, the end stage of cardiac disease, nephropathy disease, respiratory disease and cancer.
15. Allergic to pilocarpine or alcaine
16. Contraindication to ocular laser diseases.