Itchiness can be a sign of many eye problems including dry eyes, allergy, conjunctivitis,and irritation.
If you also feel pain, redness, dryness or foreign feelings, you are most likely to be suffering from dry eye syndrome. In this case, you need to drip artificial eyedrops every day.
If you suffer from excessive eye discharge, you may have conjunctivitis or pink eye. If so, you need hot compresses on daily basis and antibiotic eye drops.
If you have allergy, keep the windows open and remove the allergen.
If your eyes are irritated by foreign bodies, remove the foreign bodies and flush your eyes with lukewarm water.