Contrast sensitivity in occupational and environmental neurotoxicology: what does it really mean?

Contrast sensitivity (CS) emerged more than 30 years ago as an alternative to traditional acuity testing, and recently it has become the focus of attention in the field of neurotoxicology. CS testing may be useful for detecting defects in oculoneural processing and therefore possible chemical-induced neurotoxicity, such as solvent-induced encephalopathy. The authors' objective in this article is to introduce the concept of CS and CS testing, summarize recent reports describing its use in occupational and environmental toxicology, and challenge the validity of CS testing in its present state as a toxicological assessment. Although CS testing appears to be an attractive and cost-effective screening tool for identifying possible neurotoxicity, additional work will be required before it can become a meaningful and widely accepted diagnostic tool.