Infrared radiation and cataract II. Epidemiologic investigation of glass workers.

An epidemiologic investigation on the prevalence of cataract in glass workers is presented. The study includes 209 workers over 50 years of age exposed to infrared (IR) radiation in the Swedish manual glass industry for 20 years or more, and 298 non-IR-exposed controls. The examination includes an evaluation of the individual IR-exposure and an ophthalmological examination with special reference to the lens. In IR-exposed workers 70 years of age and older there is a statistically significant increase of aphakia and of all types of cataract, subcapsular, cuneiform and nuclear, compared to the controls of the same age group. In the same age group the risk for an IR-exposed worker to have his vision reduced by cataract to 0.7 or less is 2.5 times as high as for non-exposed controls (95% confidence interval 1.4-4.4). The risk that he will have to be operated for cataract is 12 times as high (95% confidence interval 2.6-53). It is concluded, that the occupational IR-exposure of the glass workers accelerates the development of senile changes in the lens. All workers with a high exposure to IR radiation should be equipped with adequate eye protection.