It was reserved for Niles R. Finsen, a physi cian of Copenhagen, in 1895, to utilize scientifi cally the constituent or spectroscopic elements of light as therapeutic agents. In 1832 Pictou of New Orleans published a pamphlet proving that the absence of light would prevent sup puration and pitting (scarring) in smallpox, and recommended that the eruption should be protected from air and light. Finsen, by nu merous experiments on worms and insects, con vinced himself that under red light they were comfortable, and under blue light were irri tated. Then reading Pictou's pamphlet, he inferred and advised that keeping smallpox patients in a red light would be as efficacious as darkness in preventing pock-marks by exclud ing the irritating actinic rays. If the skin is protected against the chemical rays inflamma tion will diminish and suppuration be prevented. In August 1893 Svendson in Norway and in November 1893 Benckert in Sweden used the red-light treatment with smallpox patients, and found that suppuration was abolished, scars were rare and insignificant and the disease was shortened. Even a very little daylight admitted to the room did harm, so sensitive was the inflamed skin to the actinic rays. In mild cases a clear red light was found sufficient; in severe cases a deep red light was necessary. Having proved that red light was inimical to the germs of smallpox and other eruptive dis eases, Finsen turned his attention to the effect of decomposed light on other germ-diseases, especially lupus. He proved (1) that the bac tericidal action of light is practically limited to the blue, violet and ultra-violet rays, and is greatly intensified by concentrating the rays by means of a suitable apparatus; (2) that the actinic rays so concentrated will penetrate the skin to a small degree and will go deeper if the red blood be pressed out of it — hence they would be of value in superficial cancer, baldness of microbic origin, acne, etc.; (3) that they have power to produce inflammation of the skin (erythema solace). Finsen's first case of lupus was successfully treated in 1895, with an ordinary arc electric light and a hand-lens, the red and ultra-red rays being filtered out through blue water. He then devised and used a sun apparatus consisting of two lenses of glass, one plain, the other convex, framed in a brass ring, mounted on a stand, and which admitted of adjustment and focusing. Between the lenses was a bright blue weak ammoniacal solution of copper sulphate. Discovering that the ultra violet rays were more efficacious than the violet in killing bacteria, he abolished the blue-water filter which prevented the ultra-violet rays from passing, and used clear distilled water, which sufficiently absorbs the red and ultra-red burn ing rays. Lenses of clear quartz-crystal were substituted for those of glass, it being found that they are better heat-filters and allow the chemical rays to pass almost unimpaired. As sunlight could not be depended upon for regu lar and systematic treatment, Finsen turned to the electric light.
The Finsen apparatus as now constructed consists of an arc-lamp, of from 40 to 80 am peres and one or more telescopic tubes of brass for concentration and focusing. Each tube closed is three feet four inches long and can be extended 10 inches. The head-piece of the tube has two plano-convex lenses of quartz-crystal, one with the convexity toward the light, the other with the plane surface in contact with the plane surface of the first lens. Toward the lower end of the tube there is a chamber for distilled water, designed to diminish the heat rays not eliminated by the crystal lenses. The light-rays, emerging from this bath, are con centrated by another quartz-crystal plano-con vex lens at the distal end of the tube upon the surface to be treated, the convex surface of the lens being toward the patient. To enable the rays to penetrate the surface more deeply by squeezing out the blood a compressor may be used, consisting of two quartz-crystal lenses, one plane, the other convex, with a chamber between having an inlet and outlet, through which water can be kept continuously flowing still further to cool the rays. This compressor
is either held in place by an attendant or tied on. An improvement by Hopkins of Brooklyn admits of the adjustment of the tube on a stand to suit the case to be treated, as in uterine carcinoma.
The objection to the Finsen apparatus are the cost, the usually frequent and tedious treat ment necessary—one hour a day for months— and the effects sometimes produced on the eyes. It has mainly been used in cases of lupus vul garis, and lupus erythestatosa, birth-marks, acne, and rodent ulcer. Dr. Ro'her of Switzer land has had great success in employing the sun's rays for the open air treatment of tuber culous joint affections in children.
Though Finsen's discovery may not do all that has been claimed for it, it marks a great advance, especially in the cure of lupus. Out of 456 cases treated by Finsen, 130 were cured; the disorder had not recurred in from one to five years. Cases of abdominal malignant can cer have been successfully treated in this coun try. It is claimed by originators of improved apparatus that as much can Be done therewith for lupus in 20 minutes as Finsen effected in an hour or more, that only 30 amperes, instead of 80 are necessary and that one application in several days is sufficient.
The Minim light, suggested by Minim of Saint Petersburg, which is an ordinary incan descent light, covered by a bulb of natural blue glass, with a reflector, has proved valua ble in the treatment of various forms of ulcers, in alopecia areata in contusions and in other acute injuries. Minim also offers this light as a substitute for the Finsen light in lupus.
Doctor Hopkins of Brooklyn claims the treatment by the light of the Hopkins lamp is a cure for pulmonary tuberculosis in the first stage, as well as for many cases in the second stage and that it has been of great comfort and has prolonged life in a number of instances in the third stage of the disease. The lamp con sists of a 50-ampere searchlight in a brass cylin der, with a French condensing-lens, 18 inches in diameter. It focuses at a distance of about 12 feet. The light passes through a sectional screen of blue glass, two feet square, to cut out the heat-rays and impinges upon the chest of the patient. Half-hour exposures to this light are found to be sufficient.
The German Light-Bath is used for treating the naked body by concentrated light. It con sists of a couch in a cabinet or sheet enclosure, with two or more lamps within it comprising from 40 to 80 amperes. This bath of light has proved efficacious in malnutrition, marasmus, and various forms of debility and in neuras thenia and other neurotic affections.
The mercury vapor lamp of Kronmayer, in which the rays are passed through a window of rock crystal, the crystal not filtering out the ultra-violet rays has made it possible to pro ject intense radiations and so produce very violent reactions from short exposures. By careful management it is possible thus to re move angioma, rosacea, patches of lupus, etc. In carbuncles, radiant light and heat may he employed alone to abort the condition if applied in the early stages and for long periods. Light has proved effective also in tuberculosis, peri tonitis and other tuberculous conditions.
Bibliography.—Allen, C. W., 'Radiotherapy and Phototherapy' (Philadelphia 1904) ; Cleaves, M. A., 'Light Energy' (New York 1904) ; Finsen, N. R., (t. by Sequeira, London 1901) • Finzi, N. S. 'Radium Therapeutics' (Oxford 1914) ; Hammer, W. J., 'Radium and Other Radio-Active Sub stances' (2d ed., New York 1904) ; Kassabian, M. K., (Rilintgen Rays and Electro-Therapen tics> (2d ed., Philadelphia 1910) ; Newcomet, W. S., 'Radium and Radiotherapy' (Phila delphia 1914); 'Reference Handbook of the Medical Sciences' (Vol. VII, New York 1916) ; Potts, C. S., 'Electricity: Its Medical and Surgi cal Applications> (Philadelphia 1911) ; Rogers, C. E., 'Textbook on the Therapeutic Action of Light> (Chicago 1910).