Visual Contrast Sensitivity (VCS) testing, explained

Biotoxins reduce blood flow in the smallest vessels, including those that serve the optic nerve. VCS testing measures the downstream effect: your ability to tell subtle shades of gray apart.

Why it's useful

It's fast, inexpensive, and can be repeated to track progress. A failed VCS isn't a diagnosis on its own, but combined with symptoms and history it's a strong early signal — and a way to watch recovery objectively.