The online Visual Contrast Sensitivity Test (or VCS Test) is a simple (and free) online test that can identify potential exposure to neurotoxins, biotoxins, and nutritional deficiencies in the body. These compounds have been implicated in diseases such as ADHD, CFIDS, fibromyalgia, mold illness, and Lyme disease.

What is visual contrast sensitivity testing?

According to the online VCS Test creators:

"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."

The test is based on a substantial body of research and has been taken by more than 18,000 people. The test is widely used and relied upon by individuals, healthcare professionals, and researchers from all over the world.

How to take the online VCS Test

The test takes approximately 10 to 15 minutes. If you wear glasses or contact lenses, keep them on while taking the test. I recommend taking the test in the late morning/early afternoon before your eyes are too strained from staring at screens and devices all day. You should be in a room with adequate ambient overhead lighting (but avoid screen glare), and make sure to disable any screen temperature utilities such as f.lux.

Using a tape measure or string, position (and maintain) your eye 24″ (61 cm) from the screen at eye level. The test is taken with one eye covered and the other open, first with the left eye, then the right eye:

You will be presented with a series of images with varying levels of contrast between the background patterns and parallel lines that are oriented in different directions (diagonally left, up, diagonally right, or none at all). As each image is presented, you indicate the orientation of the lines you perceive. It gets very difficult! I recommend taking a two minute break before testing your second eye to give it time to readjust after having been closed for several minutes.

My online VCS Test results

While the online VCS Test is free to take, I recommend making a small donation, which will unlock more detailed results, allow for multiple tests over time (only the first test is free), and give the ability to download reports in PDF and csv format.

I have taken the online VCS Test twice, approximately 14 months apart. Here are the results of my first test:

Here is an explanation of how to interpret the charts:

"The charts above plot the results of your contrast sensitivity test for each eye. The left axes represent contrast sensitivity, the right axes represent percentage contrast, and the bottom axes represent the spatial frequency of the parallel bars in the test images (the closer together, the higher the spatial frequency). Each plotted circle represents an image from your test, and its position corresponds to its contrast level and spatial frequency. The biotoxin columns – 6 and 12 CPD (columns C and D) – are outlined in blue. A green-filled circle indicates that you answered correctly when asked to identify the tilt of the bars, whereas a red-filled circle indicates that you answered incorrectly. The black ‘tails’ point in the direction the bars in the test images were tilted in your test, and where you answered incorrectly the red tails point in the direction you indicated.

The gray line represents the contrast sensitivity curve (average, both eyes) over the tested range of spatial frequencies among healthy research subjects as published by Dr. Shoemaker, and the red line is the curve formed by the highest level of contrast you were able to see in this test. Higher contrast sensitivity numbers are better, and if the red line is generally above the gray line you outperformed Dr. Shoemaker’s healthy research subjects. If, on the other hand, the red line dips substantially below the gray line at any point, you may have a health-affecting condition and should consider seeing your healthcare provider."

Overall Results – Positive?!?

While my results for biotoxins and other related conditions tested negative, the results indicated I may have had a nutritional deficiency:

"Though conclusive data is limited, anecdotal information suggests that impaired contrast function at 1.5 and/or 3 CPD (columns A and B) may be linked to nutritional deficiency and related conditions; cigarette and tobacco use may also affect contrast function at these spatial frequencies. In columns A and/or B you generally scored below the average among healthy test subjects; accordingly, you should consider whether nutritional deficiencies could be affecting your health.

Poor digestion and absorption can be caused by many things, including but not limited to, and in no particular order: pancreatic insufficiency; inability to produce sufficient quantities of stomach acid; liver dysfunction and inability to produce sufficient bile (and related difficulty digesting and absorbing fats); gut microbiota overgrowths, imbalances, and/or insufficiency; candida, parasite, bacterial, fungal and other like overgrowths or infections; dietary allergies, sensitivities, or intolerances; increased intestinal permeability, known as leaky gut; exposure to toxic substances (molds, bacteria, volatile organic compounds, pesticides/herbicides, heavy metals, etc.); and others."

This makes sense, as at the time I was in fact working through some gut and heavy metal/neurotransmitter issues.

Follow-up VCS Test 14 months later – negative!

Fast-forward 14 moths, and here are the results of my second VCS Test – ah, much better!

This time, I scored near perfect (96% left eye, 98% right eye), and there are no longer signs of a nutritional deficiency. However, it’s interesting to see that in the first test, my left eye performed better but on the second test my right eye performed better, and on both tests I failed at nearly the same contrast sensitivity level in column A on my left eye and column E on my right eye.

Now go try the VCS Test out for yourself!

Disclaimer: the online VCS Test creators stress that their test is a screening test and is not meant to diagnose any specific condition. If your results are positive, you should bring your results to your healthcare provider for further examination.