Abstract:  Angle closure glaucoma is (ACG) one of the main causes of blindness in Chinese. Shallow anterior chamber and narrow angle are the anatomical basis and main risk factors of ACG. Based on the current ACG mechanism and the thinking in clinical practice, the author puts forward the hypothesis of “trans-lens pressure difference and ciliary block ”. There is aqueous humor hydrodynamic block between lens and ciliary body, which called ciliary block. Trans-lens pressure difference then formed based on ciliary block. The pressure difference in front and behind the lens can promote the lens to move forward, resulting in shallow central and peripheral anterior chamber. Pupillary block which is secondary to shallow central anterior chamber, causes iris bombe and narrowing/closure of chamber angle. Aqueous humor outflow was obstructed subsequently. In clinic, we can eliminate trans-lens pressure difference by relieving ciliary block and deepening anterior chamber. That may bring new ideas for the prevention and treatment of ACG. （Ophthalmol CHN, 2021, 30: 89-96）

Key words: angle closure glaucoma, shallow anterior chamber, narrow angle, trans-lens pressure difference, ciliary block