Abstract
Purpose: :
Exposure to organic solvents affects the central nervous system and may cause neurotoxicity. Perchloroethylene (PERC), an organic solvent used in dry cleaning, has been reported to cause changes in colour vision and contrast sensitivity; however the impact of PERC on other aspects of visual function such as the perception of form (chromatic contrast sensitivity (CCS), glass pattern detection (GPP), visual search (VS)) and motion (global motion sensitivity (GMS)) remains unclear. This study compared visual function in a group of people at risk, dry-cleaners in Bogota-Colombia, with a group of people in the same city who have minimal contact with the dry-cleaning industry.
Methods: :
A case-control study of visual function in people who are working in the dry-cleaning industry for at least 1 year (n=40) with controls (n=35). Visual function measures were the contrast sensitivity function (CSF), CCS, VS, GMS and GPP. Colour vision was assessed using the Farnsworth Munsell Hue 100 test (FM-100). Neurotoxicity was assessed using a standardised neurotoxicity questionnaire (Q16). Participant PERC exposure was assessed by questionnaire.
Results: :
Q16 scores confirmed a higher level of neurotoxicity symptoms in the dry-cleaners than the controls (p<0.05). CSF in dry-cleaners was poorer than controls for spatial frequencies above 1.0 cpd (p<0.05). In dry-cleaners relative to controls, CCS was reduced for all tested colours (p<0.05), GPP was poorer by 57.3% (p<0.05), GMS was poorer by 40.7% (p<0.05). Low hue discrimination (higher error score, p<0.05) and tritan-type errors were made by dry-cleaners. There was no significant difference between cases and controls for serial and parallel VS.
Conclusions: :
Our CSF and colour vision findings agree with previous studies in dry cleaners. We additionally report a reduction in the detection of form, motion and CCS. These deficits were associated with known symptoms of neurotoxicity arising from exposure to organic solvents (Q16 score). As VS is a higher-level cognitive function, and was unaffected, the results suggest that PERC affects lower order visual functions more severely than higher level cognition.
Keywords: visual cortex • perception • ocular irritancy/toxicity testing