Annex 2

Guidance in screening for colour vision

1 Need for good colour vision

1.1 Deck officers need to be able to distinguish red, green and white navigation lights in order to be able to make correct decisions regarding the aspect of an approaching vessel, and regarding what action needs to be taken, if any, to avoid a collision. Confusion between such lights would lead to incorrect decisions being taken, with the potential for collision and resultant deaths, injuries and loss.

1.2 Ratings on lookout duty similarly need to be able to distinguish red, green and white navigation lights in order to provide correct advice to the officer of the watch.

1.3 Engineering officers and ratings on engine room duty need to be able to distinguish both warning lights (normally coloured red) from correct status lights (normally coloured white or green) and also need to be able to distinguish the colours of electrical wires when making connexions.

2 Tests

2.1 The Ishihara pseudoisochromatic tests should be used to screen seafarers in the deck and engine departments for colour vision impairment. If the tests indicate impaired colour vision, further testing should be carried out.

2.2 In the case of persons in the deck department who are required to keep watches, the further test should use the Holmes-Wright Type B lantern test. This test is conducted by some ophthalmologists and the Schools of Optometry in various Universities.

2.3 In the case of persons in the engine department whose duties may include making electrical connexions, the further test should be the UK Electricity Supply Industry Colour Vision Trade Test.

Note: For information on where to refer seafarers with colour vision deficiencies, contact the Manager, Ship Operations and Qualification at the Australian Maritime Safety Authority, on 1800 021 098.

3 Ishihara Test

3.1 The Ishihara pseudoisochromatic tests (using either the full set of 38 plates or the abridged version of 24 plates) should be used.

3.2 A satisfactory response on all plates on the first showing, or a single wrong response on first showing which is corrected on a second or third showing, should be considered to indicate ‘Normal’ colour vision. If the tests indicate impaired colour vision, further testing should be carried out.

4 Holmes Wright Type B Lantern Test

4.1 The lantern test is a practical test of a person's ability, in conditions simulated to represent a watchkeeping situation, to recognise and discriminate between navigation lights used at sea.

4.2 A lantern test is conducted by means of a Holmes/Wright type B lantern, which projects red, green and white lights viewed indirectly through a polished mirror at a virtual distance of 6 metres from the eyes. The large aperture of the lantern projects one coloured light at a time and the small apertures project 2 coloured lights side by side at a time. Each full circuit of the lantern contains 9 settings of single large apertures or 9 settings of small apertures. The small apertures of the lantern show any combination of 2 of the 3 colours.