CONTRAST SENSITIVITY MEASUREMENT IN EVALUATIONS OF VISUAL SYMPTOMS CAUSED BY EXPOSURE TO TRIETHYLAMINE

Objectives-To determine whether blurred vision caused by exposure to t riethylamine (TEA) can be detected by the measurement of contrast sens itivity. Methods-41 cold box core makers of three foundries and 82 con trol workers were examined. A detailed ocular and medical history was obtained from the subjects. The contrast sensitivity of the core maker s was measured on Monday and Friday of the same week both before and i mmediately after work and also on a third day, when air samples of TEA were collected. Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast . The changes in contrast sensitivity were used for the analysis. The results of binocular vision and the results of the dominant eye were a nalysed. Urine specimens for the analysis of TEA were collected on eve ry occasion when contrast sensitivity was measured. Results-78% of the core makers had had symptoms of blurred vision, and 31% had had troub le driving or working. The breathing zone eight hour time weighted ave rage TEA concentrations were 0.3-60 mg/m(3). The mean urinary TEA conc entration after the shift was 35 mmol/mol creatinine. Continuous monit oring showed high peaks of TEA leakage at a core making machine. Chang es in binocular visual acuity did not differ between the exposed and u nexposed workers. The contrast sensitivity of the core makers decrease d significantly at both 2.5% and 0.6% contrast during the working day. In the binocular measurements at 2.5% contrast, sensitivity decreased in 49% of the core makers and 21% of the controls (P=0.002). Conclusi ons-The blurred vision caused by exposure to TEA can be documented by measuring contrast sensitivity. The mechanism by which TEA produces sy mptoms remains an issue of further study.