Based on our study, the EyeQue Personal Vision Tracker works for almost everyone, but there are some exceptions. Some people cannot see the pattern on the vision test due to small pupils, amblyopia and visual field defects. Others will have trouble relaxing their eyes' natural focusing system which can lead to highly inaccurate vision test results. People with color blindness can also have difficulty with the test. We do not recommend the Personal Vision Tracker to those with medical conditions affecting their eyes and eyesight.