Visual Contrast Sensitivity Test - offers free or by donation visual contrast sensitivity testing, which can be used as a screen for exposure to neuro- and biotoxins — commonly overlooked causes of and/or contributors to chronic illness. Over the past several years, we’ve provided many thousands of tests to individuals, healthcare providers, and researchers, worldwide, and have helped many discover a cause of their health issues and then monitor their recovery progress.

Our contrast sensitivity test is fully calibrated to each user’s device or display, and is the most accurate, reliable, and repeatable test available online. We offer printable, downloadable, and emailable results in PDF format, visual history tracking and plotting, automated email, voice, and text message test retake reminders, and a number of other useful features and resources. is committed to helping those with chronic illness get well, and to making the world a better, healthier place.