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Shortwave automatic perimeter
Last reviewed: 25.06.2018
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[When a short-wave automatic perimeter
For examination of patients with suspected glaucoma and with one or more risk factors for its development, a SWAP test can be used. With normal achromatic perimetry. The SWAP test is suitable for examining patients with glaucoma and intraocular hypertension with changes in the fields of vision of mild and moderate severity.
How does the shortwave automatic perimeter
As an incentive use carefully chosen wavelength of blue light, and for lighting the background apply yellow light of a special color and brightness. SWAP identifies and evaluates the function of blue-yellow ganglion cells. It is believed that due to this method, the diagnosis can be made earlier, since in the early stages of glaucoma, the blue-yellow ganglion cells are selectively affected. However, the increased sensitivity of this test in comparison with the standard achromatic perimetry is the result of a reduction in the excess information flow into the visual system, which is achieved by applying blue signals on a yellow background.
Restrictions
Patients with mature dense nuclear cataracts or pronounced changes in achromatic fields of vision are not suitable for blue-yellow examination, since dense nuclear cataract delays waves of a short range and the dynamic level of falls of the achromatic visual field at SWAP rises from moderate to high. In addition, another obstacle to the interpretation of SWAP fields is the longer variability of normal objects, which complicates the differentiation of random variations from the true progression of the process.