• Key words:;
  • sunglasses;
  • ultraviolet radiation;
  • protection factor.

Solar ultraviolet radiation (UVR) has been long suspected as a causative factor in the aetiology of cataracts and recent scientific evidence has reinforced this viewpoint. The public and, in particular, outdoor workers need to take positive action to protect their eyes and the wearing of sunglasses can provide this protection. The Standards Association of Australia (SAA) has issued a standard covering the transmission requirements of sunglasses1 (AS 1067 – 1990) and sunglasses complying with this standard offer substantial protection against ambient solar UVR. However, many sunglasses offer additional protection above that required by the standard. A UVR protection factor for sunglasses, analogous to the sun protection factor (SPF) for sunscreens, would allow the public to make an informed choice when purchasing sunglasses. Measurements of the transmittance of more than 250 pairs of sunglasses and protective eye wear have been made at the Australian Radiation Laboratory. Convolution of the spectral effectiveness of UVR on the eye (action spectrum) with the solar spectrum and the sunglass transmittance can give an estimate of the amount of protection different sunglasses offer. This method provides the means for rating sunglasses and producing the relevant protection factors. Calculations show that the concept of protection factor is viable for the different sunglass types.