Protection against visible light

The eyes are of paramount importance in any consideration of the potential risks due to visible light, especially with regard to photochemical effects on the retina. Although thermal damage – that is, damage due to heating – is possible, this only occurs at higher irradiances.

The body's warning and protection system

Normally, people find it unpleasant to look at an (excessively) bright light source. It is not advisable to ignore this sensation and to deliberately look at a bright source of radiation from a short distance. This particularly applies to children, as the lenses of their eyes are more transparent to visible light (and to UV-A radiation) than those of adults.

The iris performs an important protective function: it regulates the quantity of incident light by narrowing or widening the pupil, thereby protecting the eye against overstimulation (light or dark adaptation). Involuntary or intentional reactions such as head or eye movements can also help to protect the eyes against exposure to too much light.

The blink reflex

The blink reflex primarily protects the eye from drying out and from damage due to foreign bodies, but it is also triggered by exposure to bright light. That being said, a study carried out on behalf of the Federal Institute for Occupational Safety and Health (BAuA) found that this reflex actually only occurred in a minority of subjects. Accordingly, its protective effect must not be overestimated.

Sunglasses

Appropriate sunglasses can not only protect the eyes against UV radiation and glare but also reduce the proportion of blue light reaching the retina.

Safety of light-emitting products

The manufacturer of a product must ensure that the product is safe for users if it is used as intended. Manufacturers base their safety assessments not only on laws such as the Product Safety Act (ProdSG) but also generally on relevant and, as far as possible, specific standards depending on the type of product.

Lamps and lamp systems

The photobiological safety of lamps and lamp systems is governed by the standard DIN EN 62471, which assigns lamps and lamp systems to four risk groups.

There is no risk in the exempt group (group 0). Risk groups 1, 2 and 3 represent an increasing hazard potential. The precise requirements for assignment to each group are described in the standard, and an assessment is made of the risks due to ultraviolet radiation, the risks of photochemical and thermal hazards for the retina, and the risks due to infrared radiation.

Most of the lamps used for general lighting fall within the exempt group or risk group 1. Some light-emitting diodes (LEDs) may also fall within risk group 2, as measurements by the Federal Institute for Occupational Safety and Health (BAuA) have shown. Classification into risk groups is based on “normal behavioural limitations” (risk group 1) or “aversion responses” (risk group 2). Lamps in risk group 3 represent a hazard even in the event of brief or momentary exposure. Risk group 3 is therefore not intended for general lighting.

Laser pointers

Care should be taken when handling optical radiation sources such as laser pointers or laser torches (torches whose light can be focused into an extremely narrow beam). These devices should be kept out of the reach of children.

On entering the eye, laser beams undergo additional focusing and can cause lasting damage.

In the German market, only class 1, 1M, 2 or 2M lasers are approved for use as, or in, consumer products. However, inspections by the market surveillance authorities repeatedly encounter higher classes of lasers or products whose laser class is not correctly stated.

Occupational safety

Many people are exposed to natural or artificial optical radiation in the workplace. The legal regulations concerning occupational safety apply here. For example, with reference to European Directive 2006/25/EC, the Regulation to protect workers against risks arising from artificial optical radiation (OStrV) also stipulates binding limit values for the wavelengths of visible light with respect to workers.