The EyeQue vision test does not appear to have any known side effects. The test itself is non-invasive and uses only the low intensity light from your smartphone screen. However, some people may feel mild levels of eye fatigue after their first few vision tests. Even though safe, we do not recommend testing for more than 30 minutes of continuous use with a 5 minute break for every 20 minutes of screen time. We do not recommend performing other activities such as walking, driving, or eating while taking the EyeQue vision tests. Multitasking while performing the EyeQue vision test can prove dangerous.