Glaucoma is a group of eye conditions that damage to the optic nerves. This damage is caused by an abnormally high pressure in your eye. Glaucoma is one of the major causes of blindness for people over the age of 60. It may occur at any age but is more common in older adults. Many forms of glaucoma have no warning signs. The effect might be so gradual that you may not notice any change in vision until the condition is at an advanced stage. If the cause of glaucoma is recognized early, vision loss can be slowed or prevented.