a black wand, which may be moved, against a black background. This test stimulus (pins) may be white or colored. Goldmann perimeter The Goldmann perimeter is a hollow white spherical bowl positioned a set distance in front of the patient. An examiner presents a test light of variable size and intensity. The light may move towards the center from the perimeter (kinetic perimetry), or it may remain in one location (static perimetry). The Goldmann method is able to test the entire range of peripheral vision and has been used for years to follow vision changes in glaucoma patients. However, now automated perimetry is more commonly used. Automated perimetry Automated perimetry uses a mobile stimulus moved by a perimetry machine. The patient indicates whether he sees the light by pushing a button. The use of a white background and lights of incremental brightness is called "white-on-white" perimetry. This type of perimetry is the most commonly used in clinical practice, and in research trials where loss of visual field must be measured. However, the sensitivity of white-on-white perimetry is low, and the variability is relatively high; as many as 25–50 percent of the photoreceptor cells may be lost before changes in visual field acuity are detected. This method is commonly used for early detection of blind spots. The patient sits in front of an (artificial) small concave dome in a small machine with a target in the center. The chin rests on the machine and the eye that is not being tested is covered. A button is given to the patient to be used during the exam. The patient is set in front of the dome and asked to focus on the target at the center. A computer then shines lights on the inside dome and the patient clicks the button whenever a light is seen. The computer then automatically maps and calculates the patient's visual field. Microperimetry Microperimetry assesses the macular function in a similar way to perimetry. However, fundus imaging is performed at the same time. This allows for fundus tracking to ensure accurate stimulus placement. Thus, microperimetry provides enhances the retest reliability, enables precise structure-function correlation, and allows for examination of patients with unstable fixation. Methods of stimulus presentation Static perimetry Static perimetry tests different locations throughout the field one at a time. First, a dim light is presented at a particular location. If the patient does not see