The authors, who studied the effect of light on the eye for more than ten years at the Königsberg Clinic, are enthusiastic advocates of phototherapy. A short chapter deals with the physics of light and the absorption of light by the ocular media. Theories of the general and local effects of light are discussed. The short ultraviolet ray (300 to 200 microns) exerts a marked bactericidal effect on all organisms. This effect is increased by the presence of so-called "sensitizers" in the tissues, dyes such as rose-bengal and fluorescein.
Recent studies with capillary microscopy show dilatation of the subepithelial capillaries and subsequent exudation following irradiation of the skin.
The eye differs from other parts of the body in that light may penetrate into its deeper parts in which too great a dosage of light may cause lesions. Hence, phototherapy must not be undertaken without precautions against possible damage