Lantern

Lanterns are devices that show colored point sources of light to subjects as part of an “Identification Type” color vision test, i.e. they must correctly name the color of the lights. The dots are intended to mimic the signal lights that would be used in the military or transportation industry, so the colors are generally red, green and white. The lanterns do not diagnose CVD, but rather ensure that the subject’s color vision is good enough for the specific conditions required by the testing organization. For that reason, most subjects with mild CVD can easily pass many of the lantern tests. Examples of lanterns include:

• Farnsworth Lantern (defunct, but still most common)
• Giles-Archer Colour Perception Unit (defunct)
• Martin Lantern (defunct)
• Fletcher CAM Lantern
• Edridge-Green Lantern (1891)
• Optec-900
• Board of Trade Lantern (1912, defunct)
• Holmes-Wright Lantern (1974)
• Royal Canadian Air Force Lantern
• Williams Lantern (1892, defunct)
• Sloan Colour Threshold Tester

Lanterns were invented in 1875 and have been in use since the 1890’s to screen color vision.