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There were, however, hints that the xenon arc wasalso more effective than the argon laser in preserv-ing vision. Some would take that paradox to sup-port the argument that the more substantial retinalablation also removes more of the source of a

pathogenic factor which drives the retinopathyonwards.

In the older, usually non-insulin-dependent dia-betic, vasoproliferative retinopathy is uncommonand it is the more extensive variants of "back-

ground" retinopathy which threaten vision. An in-terim report on the results of a small multicentretrial, sponsored by the British Diabetic Associ-

ation,11 was restricted to older patients with dia-betic maculopathy. In 76 patients with both eyesroughly equally affected with retinal hxmorrhages,exudates, and macular oedema with visual acuity of6/9 or less, or with circinate hard exudate involv-ing the macular region with vision better than 6/9,a randomly selected eye from each patient was sub-mitted to xenon-arc photocoagulation appliedlocally to lesions lateral to the macula, more

generally to all visible lesions, or to the centre ofcircinate exudates. More control eyes (18) thantreated eyes (8) deteriorated to blindness over a fol-low-up period of up to three years. The mean slow-ing effect of treatment on the rate of deteriorationof visual acuity was statistically significant but

small, with no obvious trend to increase with pass-ing time and most evident in patients with interme-diate degrees of visual deficit at baseline. The de-sign of this trial was good but its scale hardlyadequate to answer its primary questions.

So we now seem to have a simple, low-risk treat-ment which will, in the short term at least, delayvisual deterioration in diabetic retinopathy in pa-tients with retinal neovascularisation, especiallywhen this is more than slight and when it is accom-panied by retinal haemorrhage, and also perhaps inolder patients with maculopathy. In "ordinary"background retinopathy risk to vision is low anduninfluenced by photocoagulation. To take advan-tage of this new information (and to react promptlyto further developments) we should consider redep-loying our clinical resources. A first step should bethe repeated, systematic ophthalmoscopic screeningof patients under adequate conditions of mydriasis,and at intervals determined by the retinal appear-ance and by the type and duration of diabetes. Averification stage for questionable lesionsshould probably include fluorescein retinal angio-grams which show up small tufts of new vesselswhich may escape ordinary clinical examination.Referral of patients with treatable lesions to an

ophthalmologist with access to a photocoagulatorshould follow without delay, and treatment byaimed photocoagulation, retinal ablation, or both(and to include new vessels on the disc where the

11. Interim Report of a Multicentre Controlled Study. Lancet, 1975, ii, 1110.

argon laser is available) should be performed. Aplanned schedule of follow-up observations andadditional coagulation completes the schema.Where all of this cannot be done within a singlehospital, ad-hoc district, area, or even regional ar-rangements should be made. We must not overlookthe anxiety of the patient for his vision as heobserves the increased interest and activity centredon his eyes. Nor must we sweep into this system pa-tients with retinopathy unsuitable for treatment.For simple background retinopathy we can andneed do little but observe and improve diabetic con-trol. When extensive retinal or pre-retinal fibrosisis already present, photocoagulation may acce-

lerate contraction and hasten retinal detachment.

Very occasionally vitreous haemorrhage may occursoon after treatment, especially if large venouschannels are too closely approached. Diabetic

retinopathy is the most readily visible and clinicallyeloquent manifestation of a process which is pro-gressing in other tissues and organs, not least therenal glomerulus. Enthusiasm for photocoagula-tion, a destructive process and clearly not the endof the road in the treatment of diabetic retino-

pathy, should not deflect more general efforts to

prevent diabetic microvascular disease. This aspir-ation may well defy fulfilment until we have madea deeper penetration into the continuing mystery ofthe causation of diabetic microangiopathy.

The Future of Community MedicineTHE specialty of community medicine emerged

in Britain from a union of the Todd Commissionon Medical Education, the Hunter Working Party,and the reorganisation of the National Health Ser-vice. A turbulent infancy and childhood aré almostinevitable since each of the three parents has dif-ferent expectations of the child. And already we arehearing the cries of doom and disaster.

Before and even after Todd, medical studentsseldom opted for careers in public health or com-munity medicine, and there is concern that the

quality of entrant to the specialty is poor. Thisweek Dr HEATH and Dr PARRY (p. 82) put forwardsome ideas on the future of community medicineand they make a valuable contribution in the

emphasis they put on proper manpower planning.Perhaps the figures they cite, with their promise ofrapid promotion for the able, will encourage moredoctors to choose this sphere. HEATH and PARRYdo, however, seem to overlook some of the seriousproblems which community medicine has to tackle.The first concerns role and identity. The Hunterworking party slightly confused the issue by con-centrating on management aspects. In fact, only

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area and regional medical officers-that is, about100 out of the 700 consultant-grade posts in thespecialty—have a major managerial remit. Theother 600 should, if they are doing their jobs pro-perly, play an advisory rather than an executiverole. They should practise the art of epidemiologyand contribute towards the setting of objectives ateach level of the service, measuring and evaluatingneed, demand, and outcome. Thus the basis of

community medicine (and what makes it attrac-

tive) is the application of epidemiology to the im-provement of health care. WARREN and ACHESONlare among those who have spoken for epidemiologyand medical statistics as the two basic componentsof community medicine. And this raises another

difficulty-that of training. Entrants to com-

munity medicine, unlike those to many of the clini-cal specialties, have to acquire a deep knowledge ofsubjects they have scarcely encountered during un-dergraduate medical training. They also have toappreciate the contributions of social science, man-agement, and economics to community medicine.HEATH and PARRY emphasise the importance of

a proper academic training and criticise the consor-tium approach because of discontinuity of trainingand excessive travelling-time. In their view, full-time attendance at a university course, while notalways practicable, is the most satisfactory form oftraining. Here we disagree. Many doctors trainingfor other specialties have to combine the serviceand academic aspects of the job, and indeed separa-tion of these is one of the major criticisms that hasbeen levelled against community medicine in thepast. Modular teaching seems ideally suited to en-courage a closer relationship between theory andpractice. Finally, HEATH and PARRY discuss thecut-backs in expenditure on health and their impli-cations for community medicine. Their suggestionfor the creation of a subspecialist grade would bea step backwards and should be rigorously resisted.The problems of senior hospital medical officershave only lately ended, while the difficulties ofmedical assistants in other specialties are only justbeginning to emerge.

Community-medicine specialists contribute to

the health of population groups in a very directway. That their efforts in prevention, planning,and evaluation have not yet received the attentionthey deserve can be attributed largely to difficultiesarising from reorganisation and a change of role.Further evidence of the current difficulties of com-

munity medicine or public health comes from thework of an American committee, under the chair-manship of Dr CECIL SHEPS, on Higher Educationfor Public Health.2 As this report shows, the spe-

1 Warren, M. D., Acheson, R. M. Int. J. Epidem. 1973, 2, 371.2 Higher Education for Public Health. Report of the Milbank Memorial Fund

Commission. Prodist for the Milbank Memorial Fund, 1976.

cialty faces similar problems in the United States.There is the same concern about the quality andquantity of medical entrants to public health,although increasing numbers of people from otherdisciplines do choose this sphere of activity. Thereis concern too, to improve the training and expo-sure of graduates in public health, who should beable to identify health-related problems in a com-munity ; to develop priorities; to formulate policiesand make decisions; to perform management and

’. administrative functions; to educate the com-

munity ; to advise, consult, and support communityservice programmes; and to carry out research andevaluation. These are very similar to the British

objectives. The report also emphasises the separa-tion of research, education, and practice, and theneed to bring them together-a difficulty as muchin evidence in the U.S.A. now as it was in Britainin the past. GRUENBERG, in a personal statement asa member of the commission, makes the point, withwhich we agree profoundly, that the Sheps reportitself does not emphasise sufficiently the basic areaof endeavour in public health-namely, epidemio-logy. Only by giving proper place to epidemio-logy can community medicine attract the best

young minds, and only epidemiology can reveal theimpact of the specialty on health. Epidemiology isan exciting and productive discipline.

IMMUNE COMPLEXES IN RHEUMATIC DISEASE

THE notion that immune complexes play a part in thepathogenesis of rheumatoid arthritis and other "col-

lagen" diseases has good circumstantial support on im-munological grounds.1 2 In rheumatoid arthritis IgG,IgM complement, and rheumatoid factor have beendetected in the synovium of affected joints and the syno-vial fluid contained immune complexes. The ratio of

complement in synovial fluid to that in serum is lowerin rheumatoid than in non-rheumatoid effusions, sug-gesting local complement consumption in immune-com-plex formation. There is evidence that immune-complexdeposition is responsible for glomerular and vascularlesions in systemic lupus erythematosus (s .L.E.), andremoval of circulating immune complexes by plasma-pheresis is said to produce clinical improvement.4 Simi-lar mechanisms may operate in various forms of vascu-

litis, including polyarteritis nodosa.If such local tissue damage in the joints and blood-ves-

sels is immunologically mediated by immune complexes,what is the nature of the antigenic stimulus ? In somecases, vasculitis seems to be induced by antigens associ-ated with identifiable infections, foreign proteins, or

1. Glynn, L. E. in Clinical Aspects of Immunology, p. 1099. London, 1975.2. Ziff, M. in Progress in Immunology II, p 5. Amsterdam, 1974.3. Koffler, D., Agnello, V., Thoburn, R., Kunkel, H. G. J exp. Med. 1971, 134,

169.4. Verrier Jones, J., Cumming, R. H., Bucknall, R. C., Asplin, C. M., Fraser,

I. D., Bothamley, J., Davis, P., Hamblin, T. J Lancet, 1976, i, 709