Photic light induces eye injury by three mechanisms, i.e. heat, photochemical reaction, and physical effect. Infrared light is absorbed by water in the eye and induces cataract. Ultraviolet light induces damage on the corneal epithelium, pterygium and cataract. A case of laser pointer accident was shown as an example of retinal damage by heat and cases of accident by LED stationery and solar eclipse were introduced as examples of photochemical damage. Blue light induces oxidative stress on the retina, and daily light exposure is considered a risk factor for age-related macular degeneration. Further study would be needed on the relationship between characteristics of each light source and the effect on the eye.
I searched the literatures regarding the lights' behavior on the physiological aspects of humans to find that blue lights do not necessarily have sedative effects. In addition, concerning lights' effects on biological rhythms, it is reported that blue lights are effective; however, addition rules are not established when they try to quantify its level. With the above matters, much knowledge has been accumulated; however, it is still difficult to apply that knowledge freely concerning the blue lights' effect on physiological aspects.
Blue light has been widely used for lighting for the prevention of crime and suicide in recent years, since it was believed to have a sedative effect. In this report, we review the circumstances of blue light and illumination as lighting for the prevention of crime and suicide and their current situation. Although the number of crimes tends to decrease in the areas with lighting for crime prevention, it would not be the direct effect of blue light itself, but the combined effect of various activities for preventing crimes such as a patrol at night. In the case of lighting for suicide prevention, many railroad companies in the Tokyo metropolitan area have adopted blue light to their stations and railroad crossings. In the present situation, however, its effect is not clear since there are not enough data for objective evaluation. Comprehensive and long-term data would be needed to evaluate the effects of blue light.
The spread of Light Emitting Diode (LED) lamps and LED lamp systems has been promoting. Characteristics of LED are quite different from traditional lamps (i.e. incandescent lamp, fluorescent lamp etc.). Therefore, the requirement of the testing method development for LED lamps and LED lamp systems is increasing in the world wide. The international/regional/national photobiological safety standards for lamps and lamps systems were already published. Especially, European Union set a directive using these standards for guarantee of human photobiological safety. This directive has been valid since September 2009. All lamps and lamp systems sold in EU countries shall be tested using these photobiological safety standards. However, these standards have serious problems on the absolute optical radiometry. No one can make an accurate evaluation of photobiological safety using these safety standards except some evaluation items, some lamps and lamps systems. These problems of safety standards are reported in this paper.