Ultraviolet protection in spectacle and sunglass lenses: claims vs performance

Abstract

The need for ultraviolet protection in the natural environment has become a popular topic in the media, particularly when considered in conjunction with the depleting ozone layer and ozone hole(s). Public apprehension has been fuelled by sunglass manufacturers, distributors and importers in their attempts to sell more of their product. This has led, among other things, to the marking of sunglasses with claims of 95 per cent or 100 per cent UV protection. It has also led to a proposal for marking sunglasses with a code of Environmental Protection Factor (EPF) akin to the Sun Protection Factors of sunscreens. In this method the equivalent of a sun protection factor of 400+ is given the maximum rating of 10. In a previous report from this study, we surveyed available sunglass data to assess the level of UVR protection afforded and compliance with the sunglass standards in 253 sunglasses. We men surveyed the additional ultraviolet claims on 81 pairs of commercially available sunglasses sampled by the Federal Bureau of Consumer Affairs. We found that the great majority of sunglasses passed the various standards and the majority would have rated 10 on the EPF scale. However, a number of sunglasses did not meet the claims of UV protection placed on them by the suppliers. The suppliers are, therefore, tending to fall short in their self‐applied claims rather than the requirements of sunglass standards. We also dyed a set of piano untinted lenses using commercially available dyes and purchased lenses claimed to be treated to include 100 per cent protection to 400 nm. Judging by the performance of the lenses, there was some considerable variation in the interpretation placed on the term ‘UV 400’. The dyes fell well short, although extending the dyeing time can produce lenses with low transmittance at 400 nm. Some of the variation in claims may well arise from variations between national standards and the definition of ultraviolet wavelength limits. We hope that work can recommence on the ISO standard to enable the rationalisation of the standards and claims. (Clin Exp Optom 1993; 76.4: 136–140)

Key words:

• sunglasses
• ultraviolet
• ultraviolet protection