This is a test of commonsense. Complete the next sentence:

How to tell when you are straining your eyes
Check for sore, tired, burning or itching eyes.
If your eyes start to itch, burn or get tired, this might be a symptom of eye strain. Keeping your eyes focused for long periods of time at the same distance can sometimes cause eye fatigue.
If this happens, take a break from what you're doing. A damp washcloth laid over the eyes may help relieve the discomfort.