Glaucoma tests are a group of tests that help diagnose glaucoma, a disease of the eye that can cause vision loss and blindness. Glaucoma happens when fluid builds up in the front part of the eye. The extra fluid causes an increase in eye pressure. Increased eye pressure can damage the optic nerve. The optic nerve carries information from the eye to the brain . When the optic nerve is damaged, it can lead to serious vision problems.