Glaucoma Signs & Symptoms
Open-angle glaucoma usually affects both eyes, although IOP levels and the extent of damage to the optic nerve often differ between eyes. Because of the way the optic nerve is structured, the first nerve fibers damaged are those used for peripheral vision.
People with advanced open-angle glaucoma can have 20/20 vision when looking straight ahead but may have blind spots (called scotomas) for images located outside the center of the visual field. The damage is often not detectable on visual field tests (perimetry tests) until as much as 40 percent of the optic nerve fibers are destroyed. Eventually, the fibers needed for central vision may be lost as well.
Unlike the open-angle form, closed-angle glaucoma sometimes occurs as acute attacks that strike when IOP rises rapidly to a dangerous level. Signs of an attack include severe pain in the eye, nausea and vomiting, blurred vision, and rainbow-colored halos around lights. Attacks typically do not occur in both eyes at once, but after an initial attack, there is a 40 to 80 percent chance that a similar attack will occur in the other eye within five to 10 years if no treatment is provided.