Acute angle-closure glaucoma is mainly seen in eyes where the iris is bulging and the atrial angle is narrow or closed, because the atrial angle is very narrow or significantly closed, which can easily cause a sudden increase in intraocular pressure leading to an acute attack. Acute angle-closure glaucoma is divided into four periods according to the process of onset: 1) preclinical period, during which the eye appears to have a narrow atrial angle, shallow anterior chamber, small eye, and such signs but no symptoms are called preclinical period. 2) attack period, if the peripheral iris blocks the atrial angle causing the atrial water to flow out, the IOP will immediately rise and a series of clinical symptoms will appear. Some people can enter an intermittent remission period after an attack, which is the period when the pressure drops and the atrial angle reopens after an attack of glaucoma through timely treatment. 4. This period is called the chronic progressive phase.