VISUAL FUNCTION IN DRY CLEANERS

Abstract

Exposure to Organic Solvents (OS) used in the dry cleaning industry (DCI), has been found to be associated with neurotoxicity and changes in colour vision (CV) and contrast sensitivity (CS). The purpose of this thesis is to investigate whether the degree to which exposure to occupational levels of organic solvents (OS) in the dry cleaning industry is associated with neurotoxic symptoms and low and high level visual and cognitive functions. To address this issue a series of comprehensive studies were conducted to examine the impact of exposure to OS in both low level (contrast and colour vision) and high level visual functions (global motion, global form perception) also visual cognitive changes (visual search).The study was conducted in two populations in Colombia and Australia at risk of exposure to OS used in the DCI, but have different regulations for exposure. The range of duration of occupational exposure to OS of the participants was from 1-15 years. Control groups of people with community levels of exposure to OS used in DCI were also assessed in both countries (n=35 each site). Visual function measures assessed were CS, CV using the Farnsworth 100 Hue error score, Visual Search (VS), Glass Pattern Perception (GPP) and Global Motion Perception (GMP). Neurotoxic symptoms were assessed using the World Health Organization recommended questionnaire, the Q16, in its original form and a Likert scale modified version. Major results were that dry cleaners had poorer CS (extending to lower spatial frequencies than reported previously), hue discrimination, deficits in form and motion detection (decreased GPP and, GMS sensitivity) and higher Q16 scores than non-dry cleaners (p<0.05) for both countries. Visual search was unaffected in drycleaners and non- drycleaners in both countries suggesting that OS used in the DCI affect lower order VF but not higher-level cognition. There was no beneficial effect of specific regulations to OS exposure to DCI. Within drycleaners, severity of neurotoxicity symptoms and deficits in both low and high level visual functions were unrelated to exposure durations experience by the sample suggesting that the effects occur even with short exposures. The low and high level visual function measures had greater sensitivity and specificity in distinguishing between drycleaners exposed to OS used in the DCI and people with only community levels of exposure.