Warming and cooling the eyelids has been shown to relieve digital eye strain symptoms by melting blocked oil in the glands of the eyelid and changes in blood flow. This can sometimes cause temporary blurry vision or mild redness, twitching, or tingling of the eyelids. This is an expected response especially early on and means the oil glands in your eyes are being unblocked - resetting from all the screen time which causes them dry and become clogged. Rest continues to work long after the session ends which can cause blurriness for 15-20 mins after use. With continuous use of Rest this time period should decrease.