Tangent screen perimetry, Goldmann perimetry, octopus computerized perimetry, Humphrey perimetry.

To check for problems in the paracentral vision and side vision. This test evaluates the visual field for blurred or missing spots due to glaucoma, and to monitor these spots for stability or progression over time. It may also be used to detect visual field loss from brain tumors or strokes, from various retinal or optic nerve diseases, and sometimes to check the eyelid for orbital disorders.

When the eye looks at an object either in central or side vision, the object's image is focused on a spot on the retina, and is sent through the optic nerve into the visual pathways of the brain, eventually to the "visual cortex" at the back of the brain. If there are abnormalities anywhere along this visual pathway, a trouble spot may show up in your visual field with careful testing, even if you do not notice a problem.

Both eyes are refracted to the best corrected vision. Pupils are not usually dilated.

• You sit at a table and place your head in a chin rest, so that your head is comfortable and steady.
• Each eye is tested separately, and the eye not being tested is covered with a patch.
• The proper focusing lens (eyeglass) for your eye is placed in front of your eye for the best vision, but you do not need to wear your own glasses.
• Your eye looks straight ahead into a large bowl that has a fixed spot in the center (usually yellow or green light) on which you focus.
• The perimetrist (person doing the test) may move objects or lights of different size and brightness from the side in toward a spot where you "see" the object in your side vision. As soon as you "see" the object, you press a button to record your visual field. The same test may also be done using stationary objects of light that "blink" on and off in various parts of the visual field.
• The same test is repeated for the other eye.

Resume normal activity.

Your level of vision and attentiveness; background lighting; experience of the perimetrist; your level of vision.

An ophthalmologist can immediately assess the results.

It is noninvasive, and the results are immediate.

It may be difficult to concentrate during the test.

• Depending on results, further follow-ups, evaluation, or treatment may be recommended.
• For glaucoma testing, special photography of the optic nerve can be done using a scanning laser ophthalmoscope to measure the nerve tissue and check for problems from eye pressure.