<unk>  is a disease in which the optic nerve is damaged, leading to progressive, irreversible loss of vision. It is often, but not always, associated with increased pressure of the fluid in the eye. It is possible to have increased eye pressure without having<unk> , as well as having<unk>  without increased eye pressure.<unk>  is the second most common cause of blindness in the United States. There are many types of<unk> , including:
Open-angle (chronic)<unk> 
Angle-closure (acute)<unk> 
Low-tension or normal-tension<unk> 
Congenital<unk> 
Secondary<unk>  (including Pigmentary<unk>  and Neovascular<unk>
Glaucoma
Open-angle glaucoma
Cat eye syndrome
Ocular hypertension
Graves ophthalmopathy
Cataract
Dry eye syndrome
Diabetic retinopathy