Acute angle-closure glaucoma is a benign condition. Acute angle-closure glaucoma is a relatively common type of glaucoma, which is caused by the narrowing of the angle of the eye, resulting in the interruption of the circulation of the aqueous humor, and the accumulation of a large amount of aqueous humor inside the eye, causing an increase in intraocular pressure. After the onset of the disease, the patient will experience redness in the eyes, eye pain, eye distension, loss of visual acuity, and photophobia. Acute angle-closure glaucoma is benign, not malignant, as it does not have abnormal cell proliferation or heterogeneity, and does not invade surrounding healthy tissue or develop metastatic changes. Nevertheless, acute closed-angle glaucoma should be treated promptly, otherwise high intraocular pressure can lead to optic nerve atrophy and eventually blindness.