The VCS test or visual contrast sensitivity test is a noninvasive screening exam that can be used to help detect a biotoxin illness. It is an indicator of neurologic function in the visual system. It does not test a person’s ability to see clearly such as the Snellen eye chart does that most people are familiar with but rather tests the brain’s ability to differentiate between lighter colors and darker colors. The test is performed separately on each eye. The patient looks at a light gray circle with gray lines and is asked to identify which direction the lines are going, either left, right, or straight up. As the test progresses, the lines get thinner, closer together, and lighter in color. Those with biotoxin illness are generally unable to discern the lines as well as someone without a biotoxin illness. Approximately 92% of people with a biotoxin illness will fail the test while only about 1% of those without a biotoxin illness will fail. It is important to note that this test does not actually diagnose any illness or condition but rather is a good tool to help determine if further investigation needs to be done. It also does not indicate what type of biotoxin illness you may be suffering from. About 8% of people that actually have a biotoxin illness will pass their visual contrast sensitivity test. These individuals can still be diagnosed by using the same laboratory workup as those who fail the VCS test.
The test can be done either in a doctor’s office or as an online version. There is a fee for Dr. Shoemaker’s online version of the test. It begins by asking you to check off any symptoms you may be having. It then asks about any known or potential exposures you may have had. Finally, the contrast sensitivity portion of the test is done for each eye independently. You are immediately given a pass or fail result, and the test results can be easily printed out and given to your doctor. For Dr. Shoemaker’s online VCS test that can be done from the comfort of your home, please click here. You can also take a free visual contrast sensitivity exam where you can make a small donation by clicking here. This test does not ask about symptoms or exposures but does test the contrast sensitivity for each eye independently before giving you a positive or negative result. Complete instructions for performing the test are provided on each site.