Most people who have glaucoma experience few, if any, symptoms during early stages and you might not realize that you're losing vision until it's too late. Half of all people with loss of vision caused by glaucoma are not aware they have the disease. By the time they notice loss of vision, the eye damage is severe. Rarely, an individual will have an acute (sudden or short-term) attack of glaucoma. In these cases, the eye becomes red and extremely painful. Nausea, vomiting and blurred vision may also occur.

Generally, glaucoma causes a rapid buildup of intraocular pressure which may lead to any of the following:

• Cloudy or haloed vision
• Nausea or headaches
• Light sensitivity (photophobia)
• Excessive blinking (blepharospasm)
• Crossed or out-turned eyes (strabismus)
• One eye becoming larger than the other
• Excessive tearing (epiphora)
• Decreased vision (amblyopia)

Open-angle glaucoma, the most common form of the disease, does not present signs and symptoms at first. Eventually, however, the patient will begin to lose his or her peripheral vision. Because this damage is irreversible it is extremely important to detect the condition early: if left untreated open-angle glaucoma will lead to a total loss of vision.
People with advanced open-angle glaucoma can have 20/20 vision when looking straight ahead but may have blind spots (scotomas) for images located outside the center of the visual field. Eventually, the fibers needed for central vision may be lost as well, causing total blindness.

Closed-angle glaucoma occurs when the iris blocks intraocular fluid from draining properly. Closed-angle glaucoma may progress gradually without manifesting any symptoms until long after it has set in. Unlike the open-angle form, closed-angle glaucoma sometimes also occurs as acute attacks, as IOP rises rapidly to a dangerous level. A specific form of closed-angle glaucoma called acute glaucoma progresses rapidly and produces symptoms of severe eye pain, headache, blurred vision, nausea, vomiting, and halos. If not treated within hours, acute closed-angle glaucoma can result in permanent vision loss.

An infant or young child who has congenital glaucoma may exhibit cloudy corneas, sensitivity to light, excessive tearing, and eyelid spasm. Congenital glaucoma can be difficult to recognize because children often have trouble discerning the signs and symptoms. Consult a pediatric optician if you notice a cloudy, white, hazy, enlarged, or protruding eye. Congenital glaucoma is more common in boys than girls. A pediatric optician can help you diagnose congenital glaucoma symptoms and arrange treatment.