| Most people have some understanding of the | | | | eyestrain and fatigue in the short term. |
| damage that continuous and frequent exposure | | | | UVB (also known as medium wave light) are the |
| to the sun can have on the skin, but do not | | | | most damaging of the sun's rays and are known |
| always consider the effects on the eyes. Light | | | | to be a factor in retinal damage and the |
| contains invisible wavelengths that can cause | | | | development of cataracts. Ultraviolet B waves are |
| eventual damage to the eyes and these waves | | | | also associated with other problems that can lead |
| can be divided into visible and high energy visible | | | | to eye disease and possibly blindness. |
| (HEV) light. | | | | Ultraviolet waves of the C subtype (also known |
| While visible light is the portion that gives the | | | | as shortwave or germicidal light) are not a |
| perception of colour to the eye, HEV is the upper | | | | particular problem to the eyes, as they are |
| end of the spectrum in the violet blue band | | | | mostly absorbed by the outer atmosphere before |
| approaching ultraviolet. Excessive exposure to | | | | it reaches the earth. UVC radiation is usually found |
| ultraviolet waves can have effects later in life and | | | | in artificial sources such as germicidal light and |
| can lead to macular degeneration. | | | | mercury arc lamps. |
| Ultraviolet light waves are electromagnetic | | | | It is important when buying sunglasses to look for |
| radiation that is found to be stronger in higher | | | | those with 99-100% protection against ultraviolet |
| altitudes or in open highly reflective environments | | | | waves. The lower amount of protection is most |
| like water, snow and sand. Ultraviolet waves can | | | | likely when purchasing photochromic sunglasses |
| be divided into three types of light, UVA, UVB | | | | that require a certain amount of ultraviolet waves |
| and UVC. While most are aware that excessive | | | | to operate adequately. |
| exposure to ultraviolet waves leads to sunburn, | | | | It is not all bad news, of course 'some' exposure |
| there are other damaging effects to health that | | | | is certainly beneficially to health. All that people |
| may occur. | | | | should understand is that moderation of exposure |
| UVA (also known as longwave or black light) | | | | to ultraviolet waves should be observed for health |
| penetrates the skin and eyes and may cause | | | | purposes. |
| premature aging. It has also been linked with | | | | |