Well, generally speaking, your itchy eyes can be caused by many factors, such as the allergies, and the infection. And in common, when it occurs, it will not only make your eyes be itchy, but also make your eyes become red, even bloodshot. To treat it, you can try an over-the-counter eye drop. Besides, you can also apply omega-3 fatty acids to your diet either in supplement form. Also, you need know that foods like walnuts, salmon, flaxseed, canola or soybean oil will also be very beneficial to itchy eyes. By the way, tea tree oil can be effective too. Anyway, you can just have a try.