J. Anthony B. Spalding MB, BS, DCH, MRCP

Doctors with Daltonismand the implications for counsellingDaltonism is the most common humaninherited defect. Although there is awealth of well-researched knowledgeabout the condition, most people knowlittle about it. Those who are born withit have a double disadvantage - theysometimes fail to see what otherpeople see quite plainly, and they canbe unaware of the occasions when thisoccurs1,2. This leads to the commonattitude that they have little need foradvice3 which, in turn, presents achallenge to those who advise them.

This article gives the results of a questionnairestudy of 40 doctors with this deficiency ofwhom 35 were GPs. It is designed to show therange of difficulties they notice due to it ineveryday life and in medical practice4. It wasthought that doctors, as trained observers withsome knowledge of colour vision, would providevaluable evidence on the subject. Counselling,and an effective method of providing it, is thendiscussed.

Screening is needed to identify those whoneed counselling, but there is evidence that inrecent years this is being less frequentlyperformed for children (personalcommunication JC Read, Department of Health,1996). Prevocational screening is required forcertain occupations but there are otheroccupations for which it is rarely performed inspite of the fact that judgements of colour canbe involved in the work. Examples of the latteroccupations are medicine, nursing andveterinary surgery.

Although there is a large literature on

Daltonism, little has been published on themethod, or technique, of counselling for it. It isimportant that the method is consideredbecause of the tendency of sufferers to rejectadvice - based on the assumption that thedeficiency has little effect on the powers ofobservation. This author’s conclusions dependupon a study of the literature, personallyinterviewing 40 doctors with Daltonism, and thefact that he is a deuteranope.

The term Daltonism is used here because itis thought preferable to the other two termsmore commonly used in the UK and some otherwestern countries. The term colour blindnesscan lead to misunderstandings that may beanother reason for the rejection of advice - theyknow that they can see colours. The termcongenital colour vision deficiency is four wordsrather than one and, in addition, the wordcongenital can have unpleasant associations.Both these terms involve an attempt to explainas well as to name, and for such a complexcondition this is clearly attempting too much.The word Daltonism may need a briefexplanation, but should not lead tomisunderstandings.

MethodForty doctors who responded to letters placedin the medical press completed a questionnaire.They were then tested for the type and severityof their deficiency either in universityoptometry and visual science departments or bythe author. They were told the result of thesecolour vision tests and briefly counselled. Thestudy was conducted in 1993.

The tests used and the numbers taking them

were as follows - Ishihara Plates (39), CityUniversity (33), Farnsworth D15 (22),Farnsworth-Mansell 100-hue (22), NagelAnomaloscope (18), Pickford-NicholsonAnomaloscope (2), American Optical HRR (6).

The questionnaire was designed to elicitknowledge of - (i) the deficiency, (ii) the rangeof difficulties encountered in everyday life, (iii)the range of difficulties encountered inmedical practice, and (iv) the response ofdoctors to their difficulties in medical practice.

ResultsThe sample comprised 38 male doctors andtwo female doctors, with a mean age of 48.3.All but five were general practitioners; ninewere retired. All had received screening testsprior to the study. Of the 42 who requested aquestionnaire, 40 were included in the study.

CCoolloouurr vviissiioonn tteesstt rreessuullttss• Deutans – 33

(6 slight, 10 moderate, 17 severe)• Protans – 7

(1 slight, 1 moderate, 5 severe)

WWhhaatt aaddvviiccee wweerree yyoouu ggiivveenn wwhheenn yyoouu wweerreessccrreeeenneedd aass aa cchhiilldd oorr pprreevvooccaattiioonnaallllyy??• None - 27• Misinformed – 1• About future work - 12 (in most cases,

the advice given was very limited)

WWhhaatt ddiiffffiiccuullttiieess ddiidd iitt ccaauussee iinn eevveerryyddaayy lliiffee((ggiivvee eexxaammpplleess))??See TTaabbllee 11..

WWhhaatt ddiiffffiiccuullttiieess ddiidd iitt ccaauussee iinn mmeeddiiccaallpprraaccttiiccee aanndd aass aa mmeeddiiccaall ssttuuddeenntt??To guide the doctors, the following headingswere given - paediatrics, general medicine,surgery, dermatology, infectious diseases,otoscopy, ophthalmoscopy, mouth and throatexamination, endoscopy, test results, andcharts (TTaabbllee 22).

For medical difficulties, doctors with a milddeficiency reported fewer difficultiescompared with the combined results of thosewith moderate and severe deficiency (P<0.03;n = 40). No significant difference was foundbetween protans and deutans for the numberof difficulties reported.

IIff yyoouu hhaavvee ddiiffffiiccuullttiieess iinn mmeeddiiccaall pprraaccttiiccee,,hhooww ddoo yyoouu oovveerrccoommee tthheemm??Seventeen doctors answered that they did soby close observation or cross checking; theyspecified looking, touching, doing specialinvestigations and giving attention tolighting. Seven asked for help from others.Four gave more attention to the patient’shistory. Only one reported using a meter forreading test-tapes.

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Subject n

Dress sense 28

Décor 15

Traffic lights and signals 13

Birds, berries, flowers, insects, books, letterboxes 12

Sports and games 10

Navigation (lights and buoys) 7

Aesthetic appreciation (art and nature) 6

Maps 5

Art as a hobby 4

Naming of colours 4

Memory of colours 3

Signs (other than traffic) 3

Others: food and drink (2), bird-watching (2), 13uniform recognition (2), flushing of the face (1),philately (1), gardening (1), bank notes (1),star watching (1), blackboard (1), print (1)

Table 1 What difficulties did you have in everyday life?

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TThhee ssiiggnniiffiiccaannccee ddooccttoorrss ggaavvee ttoo ddiiffffiiccuullttiieessEight doctors thought their deficiency ofmajor significance by virtue of the fact thatthey believed that they should not practise incertain specialties and, in the case of onedoctor, because he believed he had put apatient’s life at risk by deciding that freshblood in vomit was bile. The specialtiesmentioned were - histology, haematology,bacteriology, surgery, pathology,dermatology, anaesthetics, and retinal workin ophthalmology.

There were three doctors with severedeficiencies who reported no difficulties andeight with moderate or severe deficiencieswho reported very few difficulties (less thanthree) and who gave them no or very littlesignificance.

DiscussionThe results confirmed the findings of earlierstudies showing that Daltonism causesdifficulties in everyday life5 and in medicalpractice6. The doctors in this study were selfselected and it follows that it is not possibleto extrapolate accurately to the frequency ofdifficulties in the general population.However, it does provide evidence of therange of difficulties which are noticed andhow the doctors reacted to them. Not only dothe difficulties involve activities related toefficiency and convenience, but also dangersto human life and health. Errors inrecognising navigational signals and freshblood7 as signs in medicine are examples ofsuch dangers. Difficulties therefore call forserious attention.

The number of reported difficulties wasshown to differ widely between individualdoctors. This difference occurs even withinthe group with severe deficiencies. It is likelythat those in this group who report few or nodifficulties or give them little significance arefailing to notice their difficulties. The factthat these doctors, in contrast to others, didnot report ways of overcoming difficultiestends to confirm this.

Colour provides a system forcommunicating information and people withDaltonism are not able to rely on this systemconsistently. However, they often use cueswhich, in some circumstances, effectivelyreplace reliance on colour. Brightnessdifference is an example of such a cue. Butsometimes an observation of colour ispivotal8. This occurs when a decision dependssolely on the observation of a particularcolour. A red light at sea for a navigator, andred urine for a doctor are examples. Withoutaudit or any other system of feedback, sucherrors will not necessarily be noticed. It isunlikely that one interview following colourvision testing will enable a person to make afull adjustment. This is the difficult taskpresented to the counsellor - the need notonly to provide information but also toconvince the person counselled that it isnecessary.

CounsellingAn appropriate definition of counselling is -“An enabling process in learning of newbehaviour and attitudes”9. The advice givenhere is not claimed to be definitive. It is foradults. Children require a modified form whichaccords with their understanding. They willusually need additional advice when theyare older but their parents need advice atthe time the deficiency is discovered,particularly about any limitation on futureemployment.

General adviceIn most situations, the deficiency causes nodifficulty - but the belief that it causes noneneeds confronting, particularly if thedeficiency is moderate or severe. One way ofdoing this is to show the subject photographsof various scenes and objects selected so thatthey can clearly show how failure can occur indiscrimination, naming and matching ofcolours10 . The subject can also be asked toperform the experiment at home or elsewhereby having a piece of red string placed on alawn and timing themselves to see how longthey take to find it, compared with a personwith normal colour vision.

However, gaining insight into whendifficulties occur depends on self-training andeffort, and may take several years11. Discussionwith others with normal colour vision mayhelp, both with normal and abnormal colourvision.

The subject may have experienced orcaused danger due to the deficiency. Simplylistening to their account of this may help inthe process of adjustment.

Specific advice11.. CCoonnffuussiinngg ccoolloouurrssa. The colours confused are across most of

the spectrum and not just reds, brownsand green.

b. The difficulties are in discriminating,naming, and matching colours.

c. Conditions of observation can help orhinder. Relevant factors are - lighting,atmospheric conditions, the presence orabsence of cues (particularly light/darkdifference), the nature of the background(when variegated the difficulty is greater),and the angle an object subtends at theeye (small and distant objects being moredifficult). When an object subtends anangle of less than 2˚ at the eye, thesubject with a severe deficiency (i.e.dichromat) will be completely unable todistinguish red from green. It can behelpful to know that 2˚ is the approximateangle subtended at the eye by the lastsegment of the thumb when held at arm’slength.

d. With severe deficiencies even some brightcolours can be confused. Mild deficienciesonly rarely cause difficulty.

e. Deutans and protans confuse the samecolours but protans have greater difficultywith red - they can even see it as grey orblack when it is dark or viewed in poorillumination.

22.. EEmmppllooyymmeennttAwareness of a deficiency and its severity is animportant first step in planning a career.Required standards of colour vision varyamong careers and between countries.

Subject n

Widespread body colour changes: pallor (12), 26cyanosis (9), jaundice (3), cherry-red (2)

Dermatology/rashes/erythema of skin (6) 25

Charts (13), slides (5), prints (2), codes (4) 24

Test-strips for blood and urine 22

Ophthalmology: disc pallor (3), diabetic changes (2), 18haemorrhage versus pigment (1), glaucoma (1),haemorrhage in anterior chamber (1),Kayser-Fleischer rings (1), others (9)

Body products: blood or bile in urine, 18faeces, sputum, vomit

Otoscopy: the inflamed drum (8), 14wax versus blood (1), others (5)

Microscopy (students: 11) 13

Mouth and throat conditions 9

Ishihara test giving 8

Chemistry end-points (students) 7

Colour naming 5

Tissue identification (surgery: 3) 4

What am I missing? 3

Table 2 Difficulties reported in medical practice as a student

ot

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9. Scammell B. Communication Skills,Macmillan Press Basingstoke & London.1993.

10.Spalding JAB, Arden GB. Effects of ColourBlindness. Private publication (SpaldingJAB). Weybridge, Surrey 2001.

11.Logan JS. The disability in so-called red-green blindness. An account based onmany years self-observation. Ulster Med J1977; 46: 41-45.

12.Birch J. Diagnosis of Defective ColourVision. Butterworth Heinemann (Secondedition) 2001.

13.Swarbrick HA, Nguyen P. Nguyen T, Pham P.The ChromaGen contact lens system: colourvision test results and subjectiveresponses. Ophthal Physiol Opt 2001; 21,3:182-196.

About the authorDr Anthony Spalding was a generalpractitioner in Newham, London, for 25 years.He retired 12 years ago and has since thenbeen studying the effects of Daltonism ondoctors’ clinical skills. He is a member of theInternational Colour Vision Society. Nofinancial support was received for this study.

Dr Spalding’s book - Effects of ColourBlindness - is reviewed on page 42.

To obtain information it may be necessary tocontact the occupational health departmentof the employer concerned. Careers known torequire colour standards have been listed12.For some occupations, for example medicineand nursing, private enquiry before making adecision is the only way of deciding whetherto train for it.

33.. DDrriivviinngg aa mmoottoorr vveehhiiccllee aanndd aavviiaattiioonnThere is no bar on driving a private motorvehicle but standards apply in publictransport and aviation. Caution is needed forall drivers with Daltonism in reading trafficlights and other road signs particularly inforeign countries and in responding tobraking lights

44.. IInnhheerriittaanncceeAn outline of the genetics should be given12.For the occasional complex cases, expertadvice may be needed.

55.. TTiinntteedd lleennsseessThe advantages and disadvantages should beexplained12,13.

66.. A written version of the diagnosis andadvice should be provided, and also a reportfor the prospective employer.

References1. Kalmus K. Diagnosis and genetics of

defective colour vision. Oxford: PergamonPress. 1965.

2. Pickford RW, Cobb SR. Personality andcolour vision disorder. In: Streiff EB,Verriest G (eds). Modern problems inophthalmology, 1970 Basel: Karger, 1974.

3. Evans A. Colour vision deficiency. Whatdoes it mean? J of School Nursing. 1992;8.4: 6-10.

4. Spalding JAB. Doctors with inheritedcolour vision deficiency: their difficultiesin clinical work. 1995. CR Cavonius (ed).Colour Vision Deficiencies XIII 1997. KluwerAcademic Publishers, Dordrecht: 483-489.

5. Steward JM, Cole BL. What do colour visiondefectives say about everyday tasks.Optom. And Vis. Science, 1989, 66,5:288-295.

6. Spalding JAB. Colour vision deficiency inthe medical profession. Brit J of Gen Pract.1999, 49: 469-475.

7. Reiss MJ, David A, Labowitz BS, Forman S,Wormser GP. Impact of colour blindness onrecognition of blood in body fluids.2001;161: 461-465.

8. Bradley GW. Disease, diagnosis anddecision, Chichester: John Wiley and Sons.1886.

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