802 



Report of the Committee on Colour- Vision. 



Persons to be 

 entrusted 

 with examina* 

 tion. 



Periodic 

 examination. 



Persons to be 

 examined. 



therefore exclude the colour-blind of this type (see Appendix VI). 

 It should be remarked that it is quite possible that the Holm- 

 gren wool-test might be passed satisfactorily by colour-blind 

 people of this type, more particularly when the diseased area is 

 confined to a small central spot in the retina ; in fact, this has 

 happened twice in the presence of the Committee.* The Com- 

 mittee would therefore rely rather on the form-test being 

 stringently carried out, than on instituting another colour- test 

 for this particular class of colour-blindness. 



The qualification to be required from the examiners has received 

 the careful consideration of the Committee. An examiner both 

 in the railway and in the marine services would be called upon 

 to carry out not only the tests for colour- vision but also those 

 for form, and the Committee are of opinion that he should 

 be required to obtain a certificate of competency from some 

 duly constituted authority. Testing, such as we have recom- 

 mended, requires careful training, and is not to be learnt 

 except by practice, for it requires not only a registration of 

 absolute mistakes, but also a ready observation of the manner in 

 which the candidate acts whilst under examination. The Com- 

 mittee would not insist upon the examiner being a medical prac- 

 titioner, but it is probable that a medical training would be of 

 advantage. They are further of opinion that there should be 

 a periodic inspection of the different testing stations by duly 

 qualified ophthalmic surgeons, who should report upon the con- 

 dition of the testing appliances and upon the mode in which the 

 tests are carried out ; and who might be the authorities to whom 

 an appeal from a rejected candidate should be referred. 



In no case should any test be allowed in substitution of 

 those recommended, though supplementary tests might be tried if 

 desired. The passing or rejection of the candidates should always 

 be based on the tests which have been laid down. 



As colour-blindness of the congenital character is never 

 acquired, it is unnecessary that any one who has already 

 been examined for colour-vision by efficient tests should be 

 re-examined. But as tobacco-blindness is not uncommon, 

 the form-sense of those men whose failure in vision would be 

 dangerous to the safety of the public should be tested periodi- 

 cally, say, once every three years. 



The Committee are not prepared to give a list of those posts 

 from which the colour-blind should be excluded. Pilots, look-out 

 men and officers on board ship ; engine-drivers, firemen and 



* Captain Abney prepared for the Committee pellets of baked clay of 

 about -±- inch diameter, coated with pigments in distemper of the same hues 

 as those of the wools in the Holmgren test. The images of tbese small pellets fill 

 such a minute area of the retina that those colour-blind persons were unable 

 to pick out from a small trayful of them correct matches to any of the 

 standard test colours, though they were perfectly able to pick out all those 

 coloured with any shade of blue with ease. As stated above, they passed the 

 ordinary wool-test, the colours being readily distinguished outside the 

 diseased central retinal area. 



