Acute angle-closure glaucoma is one of the most common eye diseases in middle-aged and elderly people, and it often strikes during the seasonal change. Sometimes it may be misdiagnosed as hypertension, vertigo, or acute gastroenteritis. Once acute angle-closure glaucoma occurs, it must be treated as an emergency, otherwise it can lead to blindness or even slow-closure glaucoma, which can cause serious visual impairment. The patient was 71 years old and suddenly felt severe distension and pain in the left eye at 10:00 p.m., with loss of vision, headache, nausea, vomiting, and went to a hospital ophthalmology department at 8:00 a.m. the next day to check the visual acuity of the left eye 0.1. The intraocular pressure was 72 mm gong column, and the clinical features of acute closed glaucoma were described in the medical record. However, there was no bed in the ward, so he was told to wait until noon, and no treatment was given in the meantime. The patient could not stand it and came to our hospital. Examination results: left visual acuity 0.1, intraocular pressure 70 mm, mixed congestion, corneal edema, anterior chamber extremely shallow, pupil scattered about 5 mm, loss of light response, lens slightly blurred, fundus difficult to see. The right eye had visual acuity of 0.8, intraocular pressure of 24 mm Hg, shallow anterior chamber, normal pupil, poor crystal clarity, and normal fundus. The diagnosis was left acute angle-closure glaucoma and right preclinical. The patient was immediately given 20 percent mannitol 500 ml intravenous drip, and at the same time, the pupil was dilated every 5 minutes with mucopolysaccharide ophthalmic solution, and the right eye was also dosed twice. One hour later, the patient’s symptoms disappeared, the visual acuity of the left eye was 1.0, the intraocular pressure was 16 mmHg, the cornea was transparent, and the pupil was narrowed. The visual acuity of the right eye was 1.0 and the intraocular pressure was 14 mm Hg. The pupil also became smaller. With the consent of the patient and family, an iridotomy was performed with a yAG laser. The next day, the IOP was measured at 18 mmHg in both eyes, and the IOP was observed for one week. The patient is still being followed up. In case of acute closed glaucoma attack, it should be treated as an emergency and should be handled in the outpatient clinic before admission to the hospital. Of course, if there is an empty bed in the ward, the patient can be admitted directly to the hospital.