Courtesy of Mr Richard Keeler, Curator, Museum of the Royal College of Ophthalmologists, London. Photo: Mark Thomas

Acuity of vision, field of vision and colour vision are the three most important attributes of human sight. Of these, colour vision is the most appreciated (imagine a world without colours), but least tested in routine ophthalmic examinations.

Tests for colour blindness go back to the time of Ludwig Seebeck in 1837. The first monograph on the subject was by George Wilson, Royal Professor of Technology in Edinburgh in 1855. He pointed out that a colour …