Welcome to VCSTest.com!   This website provides online visual contrast sensitivity (VCS) testing to individuals who suffer or suspect they may suffer from a health condition that affects contrast sensitivity, and to healthcare professionals and researchers worldwide.

Visual contrast sensitivity testing measures your ability to see details at low contrast levels and is often used as a nonspecific test of neurological function.  Similar in form to a standard audiometry hearing test, a VCS test generally involves the presentation of a series of images of decreasing contrast to the test subject and the recording of the contrast levels where patterns, shapes, or objects can or cannot be identified.  The results of the test can then be used as an aid in the diagnosis of visual system dysfunction.

Many things can affect the ability to perceive contrast.  These include nutritional deficiencies, the consumption of alcohol, drug/medication use, and exposure to endogenous or exogenous neurotoxins and/or biotoxins, including volatile organic compounds (VOCs), venom from animal or insect stings or bites, certain species of mold and the mycotoxins and microbial VOCs they produce, cyanobacteria, dinoflagellates (particularly Pfiesteria and Ciguatera), parasites, heavy metals like mercury and lead, and the pathogens responsible for Lyme disease and its common co-infections.   For more information, please see our Research resources.

VCS testing, by itself, is generally not diagnostic for any specific condition (including either mold or neurotoxin exposure), but a positive result may suggest the existence of a health and life-affecting subclinical process.  If your results are positive, you could have a number of different conditions and should see your healthcare provider.

VCSTest.com contrast sensitivity tests have been taken over 18,000 times and are widely used and relied upon by individuals, healthcare professionals, and researchers all around the world.  Our new Online Contrast Sensitivity Test™ - the OCST™ - is identical to the Functional Acuity Contrast Test, or FACT^®, used by Dr. Shoemaker and others involved in neurotoxin research in terms of contrast levels and spatial frequencies tested, but it uniquely features on-screen display size and gamma calibration to ensure that results are accurate and valid regardless of the type, size, and settings of the device used to test.  Additionally, OCST test images are generated dynamically in software, which ensures that images are of the highest quality and that the test is different each time you take it.  Our biotoxin-illness pass/fail algorithm is the same proven algorithm used by Dr. Shoemaker, though the OCST also scores performance at the other tested spatial frequencies using criteria developed from current contrast sensitivity-related research.   We provide up to 2 pages of enhanced and expanded results and interpretation, including research-based information on what deficits at each of the tested spatial frequencies might suggest.  Results are immediately available on-screen, and in printable and forwardable PDF format for a nominal donation.


Testing is free or by donation for individuals.  Currently, new individual users receive one free test initially, though free results are limited to a positive/negative determination and test scores.   If you need to test again, or if you'd like a detailed results interpretation and printable and forwardable PDF, we request a small donation (though we're happy to give free tests).

VCSTest.com accepts donations via PayPal in US dollars, and via credit card in 138 currencies across 225 countries, territories, principalities, and microstates, with no foreign exchange or extra credit card fees.  Donation amounts are adjusted to your economy, and the amount of one test is generally proportional to the cost of a moderate lunch; in the United States we ask for a donation of USD $10.00 for detailed results and additional tests, though packages of 3, 5, and unlimited test credits are available at reduced rates.  If you cannot donate but need detailed, printable, forwardable PDF results, or to test again, please contact us after establishing your account and we'll be happy to upgrade your results or provide free test credits.


Generally, testing takes between 10 and 15 minutes.

Register for a free account, which will enable:

• storage and retrieval of previous test results;
• visual tracking and plotting of test scores on an interactive chart; and,
• free automatic email test retake reminders!

Additionally, if you make a donation you'll receive:

• detailed results interpretation and analysis;
• email and downloadable test results in PDF format which can be printed and/or forwarded to your doctor;
• email and downloadable PDF and CSV test results summaries; and,
• free, optional automated voice and SMS test retake reminders.