青光眼（Glaucoma）是一系列会导致视神经受损，进而造成视力丧失的眼疾。当中最常见的是隅角开放性青光眼，相反地，另一类型的隅角闭锁性青光眼则相当少见。也有部分青光眼患者的眼压是正常的。 隅角开放性的疾病进程相当缓慢而且不会有疼痛感。在周边视野开始产生模糊感后，中心视力也会因为没有接受妥善治疗而慢慢受损，最后则有可能会失明。隅角闭锁性的疾病发展有可能为渐进或突发。若为突发性的，则有伴随急性眼痛、视力模糊、瞳孔放大、眼睛红痛与晕眩的可能。由青光眼所引起的视力丧失，若一旦发生了，则这样的伤害将会是永久性的。

Glaucoma is a group of eye diseases which result in damage to the optic nerve and vision loss. The most common type is open-angle glaucoma with less common types including closed-angle glaucoma and normal-tension glaucoma. Open-angle glaucoma develops slowly over time and there is no pain. Side vision may begin to decrease followed by central vision resulting in blindness if not treated. Closed-angle glaucoma can present gradually or suddenly. The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea. Vision loss from glaucoma, once it has occurred, is permanent.