In most cases, people may experience symptoms such as a change in vision or eye pain that require a immediate medical attention. If you experience any of these following symptoms, see an eye doctor right away.1, Flashing lights, floaters, or a gray shadow in your vision. 2.Any loss of vision, particularly if sudden or in one eye.3.Eye pain. 4. Eye injury. 5. Persistent discomfort in the eye.6. Red eye. 7. Eye discomfort if you are a contact lens wearer. 8. Blurred vision.9.Eye surgery complication.