995.4.74: Pseudo-Isochromatic Plates, 1905-1953

Additional Images

995.4.74: Pseudo-Isochromatic Plates.
Image No. 2390 ; Photographer: Helen Kingsley

Object Description

R.C.A.F. modification of the Ishihara Colour Test for protan and dutan defects. Consisting of 25 coloured Pseudo-Isochromatic plates. The plates are held in a slip sleeve box contained in an outer case. The test consists of coloured plates on black cards, each of which contain small coloured dots varying in size, colour and intensity. Within the pattern are dots which form a number visible to those with normal color vision and invisible, or difficult to see, for those with a color vision defect. The card number and dot number are given on the reverse side of the card in silver print.

Object Classification

Accession Number: 995.4.74
Collection: Ophthalmology
Date: 1905-1953

Object Dimensions

  • Height: 19.8 cm
  • Width: 14.6 cm
  • Depth: 3.6 cm

Object Parts

  • a) Box cover
  • b) Slip sleeve box
  • c) Card 1
  • d) Card 2
  • e) Card 3
  • f) Card 4
  • g) Card 5
  • h) Card 6
  • i) Card 7
  • j) Card 8
  • k) Card 9
  • l) Card 10
  • m) Card 11
  • n) Card 12
  • o) Card 13
  • p) Card 14
  • q) Card 15
  • r) Card 16
  • s) Card 17
  • t) Card 18
  • u) Card 19
  • v) Card 20
  • w) Card 21
  • x) Card 22
  • y) Card 23
  • z) Card 24
  • aa) Card 25

Object Materials

  • card,
  • cardboard,
  • gold print,
  • paper,
  • printing ink,
  • silver print,
  • textile

Acquisition Detail

  • Manufacturer: American Optical Company
  • Owner: Dr. Andrew Davidson
  • History of Use: Used by Dr. Andrew Davidson [1885-1972] a military doctor and a noted dermatologist who served in both WW1 and WW2. He served in France as an officer [Captain] for the Royal Army Medical Corps (1915-1917) and in the Canadian Army Medical Corps (1917-1919), specializing in the diagnosis and treatment of venereal and skin diseases. In 1939, he returned to active military service with the rank of Lieutenant-Colonel and was involved in the institution of the PULHEMS system. This is a system for classification of soldiers, the acronym stands for: P – physical capacity, U – upper extremity, L – locomotion, H – hearing, E – eyesight, M – mental capacity, S – stability of emotions. After the war, Dr. Davidson moved from Winnipeg to Vancouver, where he was in practice in association with his son, Dr. Kenneth Davidson. In 1947, Dr. Davidson was elected as the founding president of the Canadian Dermatological Association, and was a winner of the Sabouraud Medal for research in dermatology.