Who fails lantern tests?

Abstract

A battery of clinical colour vision tests was given to a group of 100 observers with abnormal colour vision who were also tested on the Farnsworth lantern and the Holmes-Wright lanterns types A and B. It was found that clinical colour vision tests are imperfect predictors of lantern test performance. However, observers classified as having a 'severe' colour vision defect were found to fail the lantern tests but only one half to two-thirds of those who fail the lantern tests can be identified in this way. It is not possible to identify with certainty any of the people likely to pass the lantern tests: about one-third to two-thirds of observers classified as being mildly affected fail the lantern tests. The Farnsworth D-15 and City University tests were found to be the best predictors of lantern test performance but other tests such as the Nagel anomaloscope, the H-16, L'Anthony's desaturated test can also be used. The lack of a strong correlation between clinical tests and the recognition of the small coloured stimuli presented by the lantern tests suggests that clinical tests do not test the same aspect of colour vision that is important to the recognition of signal lights. For this reason lantern tests should be retained for occupational testing of colour vision.

Color Vision and Fatigue: An Incidental Finding

“…This discrepancy raises concerns about the sensitivity of the CN Lantern for failing individuals with more severe defects. However, the result that a small number of individuals with a severe defect have passed the CN Lantern is consistent with other reports that a small of number of individuals with severe color vision defi ciencies have passed other lantern tests ( 2,4,8 ).…”

Assessment of inherited colour vision defects in clinical practice

“…In essence, these investigations show that almost all patients (more than 95 per cent) who fail the Farnsworth D15 test will make errors identifying the colours of signal lights [46][47][48] and surface colourcodes. 39, [49][50][51][52] Of those who pass the Farnsworth D15 test most (approximately 75 per cent) will be able to recognise surface colour-codes without error or very few errors.…”

“…48 Fewer are able to pass lantern tests such as the Holmes-Wright and Spectrolux lanterns used in the UK and some European countries because they simulate more difficult conditions of observation. 46,56,57 Table 5 summarises the advice that could be given to patients about the occupations that have a colour vision standard or for which abnormal colour vision is likely to be a handicap. Patients with abnormal colour vision who have yet to settle on a career could be given a photocopy of Table 5 to help choose a suitable career.…”

“…Will have problems with signal lights and will fail lantern tests. [46][47][48] Will be excluded from occupations that use a lantern test to assess colour vision. …”

From beach lifeguard to astronaut: occupational vision standards and the implications of refractive surgery

“…The Optec 900, said to be more stringent than the Farnsworth test, has since come into use 31. Lantern tests are secondary colour vision tests that do not exclude all anomalous trichromats,32 but pick up difficulties in colour signal light recognition better than clinical tests such as the Nagel anomaloscope 33. The Holmes–Wright Lantern, devised in the UK in 1974, is no longer produced and is being superseded by the improved Fletcher–Evans CAM Lantern Test (http://www.evansinstruments.co.uk).…”