Ultraviolet A, Blue Light and Children

By Elaine Kitchel, Low Vision Research Associate, American Printing House for the Blind

For years now, professionals in the fields of light energy and vision have known about the hazards of ultraviolet (UV) light. Even experts differ as to the exact wavelength of UV light waves. Generally speaking, however, UV light is defined as the part of the spectrum which is divided into UV-A (380-315 nm), UV-B (314-280 nm), and UV-C (279-200 nm).

UV-C and UV-B, though harmful will not be discussed here since they are virtually absent from indoor light. However, a recent boom in the number of practitioners using blacklight activities has brought about high levels of exposure to UV-A and blue light for a significant number of children. Why is that a problem? Recent research in cellular biology has shown that exposure to the UV-A and blue light waves emitted by blacklight tubes can have long term negative effects for persons exposed to it, especially children.

Blue light, that part of the visible spectrum which ranges for 500 to 381 nm, makes up half of the light emitted from black light range. However, until recently, little had been offered in the way of information about how blue light, and UV-A affect the eye structures of children.

Bear in mind that as the lens of the eye ages, it begins to yellow. This yellowing gives adults some, but not adequate, protection against UV-A and blue light. However, children have not lived long enough to have this yellowing. Therefore UV or blue light which enters the eye will strike the retina at full-strength exposing not only the retina, but the lens to damage. Dr. W. T. Ham, who has conducted research on the effects of UV and blue light has written,

Most authorities now believe that the near UV radiation absorbed throughout life by the lens is a contributing factor to aging and senile cataract. Thus by protecting the retina from near UV radiation, the lens may become cataractous. My own personal opinion is that both the retina and the lens should be protected throughout life from both blue light and near UV radiation. (Ham, 1983, p. 101)

If Dr. Ham is concerned about exposure to UV and blue light from the exposures of daily living, one has to wonder what he would say about young children who are being exposed several times a week to UV and blue light from blacklight activities. Many of these children receive no protection for their eyes, and for those that do, most of it is woefully inadequate.

What is it about UV-A and blue light that make them hazardous? Tests done by Drs. Ham and Chen show that when UV-A and blue light strike the retina the light waves inhibit the formation of a chemical called cytochrome oxidase. This chemical is an important part of retinal cells because it transports oxygen to photoreceptor and other retinal cells. Without cytochrome oxidase, the cells become deprived of oxygen and eventually die. When enough cells die, retinal degeneration occurs.

Many people have said that UV-A and blue light will not harm children if the length of time of exposure is limited, or if frequency of exposure is limited. In Sweden, Dr. E. Chen exposed the retinas of mice to moderate levels of blue light. Two days later, lesions showed up on the rodent's retinas after only 4 minutes of exposure. Similar research was conducted by Drs. Gorels and van Noren. They concluded that the retinal damage done was a feature of the wavelength, not duration or frequency of exposure. This means, that even a short exposure to blue light, without adequate protection, can cause retinal damage.

The experiments of Drs. Chen, Gorels, and van Noren were later done on primates with similar results. The eyes of rhesus monkeys are very similar to our own. Drs. Sperling, Johnson and Hawerth exposed the retinas of rhesus monkeys to blue light and found,

...extensive damage in the retinal pigmented epithelium form absorption of energy by the melanin granules. It should be pointed out that the damage seen, including the macrophagic activity, disrupted cells and plaque formation, is characteristic of that seen by Ham et al. (1978), and others in what he calls the photochemical lesion.

Often the lesions from UV-A and blue light are scattered on the retina. It is only when enough of them appear and coalesce that one begins to notice a vision loss. This is why vision loss is not immediate, but often takes many years to manifest. This is the reason why children, especially ones who already are suffering from a vision loss, must be adequately protected.

Protection against blue light damage is simple. However, most practitioners who use blacklight tubes do not use adequate protection. Most who bother to use any protection at all, use clear polycarbonate lenses for the child and none for themselves. It cannot be emphasized strongly enough both practitioner and child who are exposed to the light emitted from blacklight tubes must be protected. Yellow polycarbonate lenses offer complete protection, in most cases, against blue light hazard. Various goggles and lenses are available from such vendors as NOír Medical Technologies and Solar Shield. Objects will still appear to fluoresce if viewed through a yellow polycarbonate filter.

With adequate protection being inexpensive and available, practitioners should be vigilant in their efforts to protect the eyes of themselves and of the children who are exposed to the damaging effects of UV-A and blue light.

You may read more about blue light hazard by requesting a copy of "The Effects of Blue Light" from Elaine Kitchel at APH, 1839 Frankfort Avenue, Louisville, KY 40206-0085.