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Short-wave automated perimetry
Last reviewed: 04.07.2025
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Short-wavelength automated perimetry (SWAP) has a higher sensitivity for diagnosing early stage glaucomatous damage than standard automated perimetry.
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When shortwave automatic perimetry is used
The SWAP test can be used to evaluate patients with suspected glaucoma and one or more risk factors for its development. with normal achromatic perimetry. The SWAP test is suitable for examining patients with glaucoma and intraocular hypertension with mild to moderate visual field changes.
How does shortwave automatic perimetry work?
A carefully selected wavelength of blue light is used as a stimulus, and yellow light of a special color and brightness is used to illuminate the background. SWAP isolates and evaluates the function of blue-yellow ganglion cells. It is believed that this method can be used to make a diagnosis earlier, since blue-yellow ganglion cells are selectively affected in the early stages of glaucoma. However, the increased sensitivity of this test compared to standard achromatic perimetry is the result of reducing the excess information entering the visual system, which is achieved by using blue signals on a yellow background.
Restrictions
Patients with mature dense nuclear cataracts or severe achromatic visual field changes are not suitable for blue-yellow examination, since dense nuclear cataracts delay short-range waves and the dynamic level of achromatic visual field loss in SWAP increases from moderate to severe. In addition, another obstacle to interpreting SWAP fields is the longer-term variability of normal objects, which complicates the differentiation of random variations from true progression of the process.