How it began
Niels Ryberg Finsen was born in the Faroe Islands in 1860, grew up in Iceland and moved to Copenhagen in 1882 to study medicine. He noticed that sunlight made him feel more energetic, which led him to study the medical effects of light. In 1895 he treated patients who had lupus vulgaris, a tuberculosis of the skin, with concentrated ultraviolet light, and in 1896 he reported preliminary results in 11 patients.
Before it existed
Since the 1870s it had been known that ultraviolet light inhibits bacteria. Lay people and alternative practitioners had reported good effects of concentrated sunlight on lupus vulgaris, and two patients had been treated with electric light. Finsen judged those exposures too brief to work and objected that they relied on the burning effect of light, which caused substantial harm.
How it works
Finsen found that the useful effect lay in the short-wave part of the spectrum and that blood blocked the rays. He built equipment that concentrated light 15 times onto an area about 2 cm across, used pressure devices to keep blood out of the treated skin, and made lenses of crystal instead of glass. This avoided burning and scarring. Patients were treated for two hours a day for several weeks on the same spot.
How it spread
Finsen set up a center in Copenhagen. Most patients were poor, so it was supported by sponsors, the municipality and a charity. In 1902 he presented results for 804 patients in Berlin, reporting that 94 percent of 737 assessed cases responded favorably. He warned that inferior lamps then coming onto the market might not give the same results.
What lasted
Finsen received the 1903 Nobel Prize in Physiology or Medicine for opening "a new avenue for medical science." He was too ill to attend and died in Copenhagen in 1904. According to the Nobel Prize organization, light therapy was widespread for a time but was eventually supplanted by antibiotics.
