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COLOUR VISION TESTS.
50 Sir Thomas IHorder, Physician in Ordinary to the Lady Barrett, M.S., Dean of the London (Royal Free Prince of Wales, and Physician, St. Bartholomew’s Hospital) School of Medicine for Women. Mr. Comyns Berkeley, Surgeon, Middlesex Hospital, and Hospital. a, member of the Radium Commission. Dr. F. N. Kay Menzies, Medical Officer of Health for the Sir Robert Bolam, Honorary Physician, Royal Victoria County of London. Lord Moynihan, President of the Royal College of Surgeons ; Infirmary, Newcastle-on-Tyne, and past Chairman of Council, . British Medical Association. Consulting Surgeon, Leeds General Infirmary, and Emeritus Dr. H. B. Brackenbury, Chairman of Council, British Professor of Surgery, Leeds University. Medical Association. Mr. H. J. Paterson, Senior Surgeon, London Temperance Mr. H. W. Carson, Senior Surgeon, Prince of Wales’s Hospital, and Honorary Secretary, Fellowship of Medicine General Hospital, Tottenham. and Post-Graduate Association. Dr. H. G. Dain, Chairman of Insurance Acts Committee, Dr. Harold Pritchard, Physician, West London British Medical Association. Hospital. Lord Dawson, Physician in Ordinary to the King, and Sir Holburt J. Waring, Surgeon, St. Bartholomew’s Physician, London Hospital. Hospital. Prof. H. R. Dean, Professor of Pathology, Cambridge Mr. Heseltine will act as secretary of the committee, i University. Sir Walter M. Fletcher, F.R.S., Secretary of the Medical and all communications on the business of the Research Council. committee should be addressed to him at the Ministry Prof. G. E. Gask, Professor of Surgery, London University, of Health, Whitehall, S.W.I. and a member of the Radium Commission.
CORRESPONDENCE pseudo-isochromatic tests and the fact whether he was dangerously colour-blind or not was ascertained subseTo the Editor of THE LANCET. quently. Ten of the 38 cases were passed and 28 SiR,-In the report of the Section of Laryngology, rejected. Of the 28 who were failed 16 failed with all Royal Society of Medicine, appearing in THE LANCET three pseudo-isochromatic tests, but 12 of those of June 28th, there are observations with regard to rejected passed Ishihara completely and 11passed avertin on which I beg to offer some comment. It Stilling. Of those who were passed 7 showed defects was stated, for example, by one speaker, that " the with my card test, and of those who failed all were state of unconsciousness for two hours and sleepiness rejected by my card test, in most cases failing very for three days was, especially in laryngeal conditions, badly, as for instance not reading card 8, a yellowsomething strenuously to be avoided. The absence J green C on an orange ground. The explanation of the of laryngeal reaction in these patients after the use difference is that a test for a dichromic will not necesof avertin was very alarming." These remarks were sarily detect a trichromic who has three colour called forth and no doubt justified by the preceding sensations red, green, and violet but no yellow sensastatements of others which unfortunately are not tion, and who is obviously dangerous as shown by the recorded, but I would like to point out that those examination with the lantern and spectral tests. In observations do not apply to the usual effects of my card test also the pattern is the same on every avertin when correctly used. When so employed it card, so that the examinee has to judge by colour alone has never to my knowledge caused sleepiness for threeI and cannot follow the design of the artist. days, and what is more important, the laryngeal An important point to note is that a test which is reactions return, if they are ever abolished, within a difficult to the normal-sighted is not necessarily short space of time. This is secured by giving difficult to the colour-blind. This is shown by the avertin without any preceding opiate or similar drug. number of colour-blind persons who can read Stilling’s I think it would be a pity if the use of avertin, which I plates numbered 9 and 10, the reading of which is have seen to be of enormous benefit to suitable patients supposed to indicate very good colour perception. In undergoing operations on the throat, were to be fact, a test may be constructed which can be read by avoided because of a fear which is really not well the colour-blind but not by the normal-sighted. founded. I am, Sir, yours faithfully, Nagel’s anomaloscope is not a satisfactory test as a J. BLOMFIELD. London, June 30th, 1930. man may be anomalous without being colour-blind AVERTIN IN LARYNGOLOGY.
SIR,—In
COLOUR VISION TESTS. To the Editor of THE LANCET. an annotation on p. 1360 (June
21st)
youJ
dealt with the international standardisation of colour vision tests. The two essentials of a practical test colour-blindness are that dangerously colour-blind persons only should be rejected by it and that no dangerously colour-blind person should escape detection. The wool test with five test colours allows .50 per cent. of dangerously colour-blind to escape detection and of those rejected by it 50 per cent. are practically normal-sighted. The pseudo-isochromatic tests in common use are those of Stilling, Ishihara, and my card test. In order to ascertain the relative merits of these three tests, 38 consecutive, referred or appeal cases were examined at the Board of Trade with the’ following results. None of these cases was examined by me alone ; at least three persons and often more were present at all the examinations. - --In every case Capt. Ellery or Capt. Dowdy and the recorder were present. Each candidate was first examined by the;
and 90 per cent. of the colour-blind agree with the normal equation. I am, Sir, yours faithfully, F. W. EDRIDGE-GREEN. Board of Trade, S.W., June 28th, 1930.
for
SUSCEPTIBILITY TO HAY-FEVER. To the Editor of THE LANCET.
SIR,-There is
some evidence that susceptibility hay-fever is hereditary. It is also a character usually well marked and comparatively easy to trace amongst members of a family. At this time of the year many general practitioners must meet with hayfever cases whose genetical history could be discovered without much difficulty. Should any of your readers come across such cases and be willing to obtain records of the incidence of hay-fever amongst members of the family over (say) four generations, I should be glad to receive them as I am collecting records of this kind. I am, Sir, yours faithfully,
to
H. G. THORNTON. Bacteriology Department, Rothamsted Experimental Station, Harpenden, June 27th, 1930.
CORRESPONDENCE pseudo-isochromatic tests and the fact whether he was dangerously colour-blind or not was ascertained subseTo the Editor of THE LANCET. quently. Ten of the 38 cases were passed and 28 SiR,-In the report of the Section of Laryngology, rejected. Of the 28 who were failed 16 failed with all Royal Society of Medicine, appearing in THE LANCET three pseudo-isochromatic tests, but 12 of those of June 28th, there are observations with regard to rejected passed Ishihara completely and 11passed avertin on which I beg to offer some comment. It Stilling. Of those who were passed 7 showed defects was stated, for example, by one speaker, that " the with my card test, and of those who failed all were state of unconsciousness for two hours and sleepiness rejected by my card test, in most cases failing very for three days was, especially in laryngeal conditions, badly, as for instance not reading card 8, a yellowsomething strenuously to be avoided. The absence J green C on an orange ground. The explanation of the of laryngeal reaction in these patients after the use difference is that a test for a dichromic will not necesof avertin was very alarming." These remarks were sarily detect a trichromic who has three colour called forth and no doubt justified by the preceding sensations red, green, and violet but no yellow sensastatements of others which unfortunately are not tion, and who is obviously dangerous as shown by the recorded, but I would like to point out that those examination with the lantern and spectral tests. In observations do not apply to the usual effects of my card test also the pattern is the same on every avertin when correctly used. When so employed it card, so that the examinee has to judge by colour alone has never to my knowledge caused sleepiness for threeI and cannot follow the design of the artist. days, and what is more important, the laryngeal An important point to note is that a test which is reactions return, if they are ever abolished, within a difficult to the normal-sighted is not necessarily short space of time. This is secured by giving difficult to the colour-blind. This is shown by the avertin without any preceding opiate or similar drug. number of colour-blind persons who can read Stilling’s I think it would be a pity if the use of avertin, which I plates numbered 9 and 10, the reading of which is have seen to be of enormous benefit to suitable patients supposed to indicate very good colour perception. In undergoing operations on the throat, were to be fact, a test may be constructed which can be read by avoided because of a fear which is really not well the colour-blind but not by the normal-sighted. founded. I am, Sir, yours faithfully, Nagel’s anomaloscope is not a satisfactory test as a J. BLOMFIELD. London, June 30th, 1930. man may be anomalous without being colour-blind AVERTIN IN LARYNGOLOGY.
SIR,—In
COLOUR VISION TESTS. To the Editor of THE LANCET. an annotation on p. 1360 (June
21st)
youJ
dealt with the international standardisation of colour vision tests. The two essentials of a practical test colour-blindness are that dangerously colour-blind persons only should be rejected by it and that no dangerously colour-blind person should escape detection. The wool test with five test colours allows .50 per cent. of dangerously colour-blind to escape detection and of those rejected by it 50 per cent. are practically normal-sighted. The pseudo-isochromatic tests in common use are those of Stilling, Ishihara, and my card test. In order to ascertain the relative merits of these three tests, 38 consecutive, referred or appeal cases were examined at the Board of Trade with the’ following results. None of these cases was examined by me alone ; at least three persons and often more were present at all the examinations. - --In every case Capt. Ellery or Capt. Dowdy and the recorder were present. Each candidate was first examined by the;
and 90 per cent. of the colour-blind agree with the normal equation. I am, Sir, yours faithfully, F. W. EDRIDGE-GREEN. Board of Trade, S.W., June 28th, 1930.
for
SUSCEPTIBILITY TO HAY-FEVER. To the Editor of THE LANCET.
SIR,-There is
some evidence that susceptibility hay-fever is hereditary. It is also a character usually well marked and comparatively easy to trace amongst members of a family. At this time of the year many general practitioners must meet with hayfever cases whose genetical history could be discovered without much difficulty. Should any of your readers come across such cases and be willing to obtain records of the incidence of hay-fever amongst members of the family over (say) four generations, I should be glad to receive them as I am collecting records of this kind. I am, Sir, yours faithfully,
to
H. G. THORNTON. Bacteriology Department, Rothamsted Experimental Station, Harpenden, June 27th, 1930.