the light, it is made gradually brighter until it is seen. The minimum brightness required for the detection of a light stimulus is called the "threshold" sensitivity level of that location. This procedure is then repeated at several other locations, until the entire visual field is tested. Threshold static perimetry is generally done using automated equipment. It is used for rapid screening and follow-up of diseases involving deficits such as scotomas, loss of peripheral vision and more subtle vision loss. Perimetry testing is important in the screening, diagnosing, and monitoring of various eye, retinal, optic nerve and brain disorders. Kinetic perimetry Kinetic perimetry uses a mobile stimulus moved by an examiner (perimetrist) such as in Goldmann kinetic perimetry. First, a single test light of constant size and brightness is used. The test light is moved towards the center of vision from the periphery until it is first detected by the patient. This is repeated by approaching the center of vision from different directions. Repeating this enough will establish a boundary of vision for that target. The procedure is repeated using different test lights that are larger or brighter than the original test light. In this way, kinetic perimetry is useful for mapping visual field sensitivity boundaries. It may be a good alternative for patients that have difficulty with automated perimetry, either due to difficulty maintaining constant gaze, or due to cognitive impairment. Stimulus settings and photoreceptor-specific perimetry Photopic perimetry The most commonly performed perimetry test uses white stimuli on a bright white background (photopic white-on-white testing). This tests isolated L- and M-cone function and is applied in the setting of glaucoma. Scotopic perimetry Following 30 minutes of dark-adaptation, it is possible to selectively test rod function using short-wavelength (blue) stimuli on a dark background. Today, it is also possible to perform this type of examination in eyes with unstable fixation using scotopic microperimetry. See also Bitemporal hemianopsia (loss of peripheral vision). References External links "Amsler Grid" Test from Ossibus Software Diagnostic ophthalmology