Allergies can affect the eyes primarily causing itchy eyes and redness. Generally when the trigger is environmental, the nasal cavity gets inflamed and is affected. There are many conditions that can cause discomfort in the eyes such as infection that may be mistaken for allergies. It is important to discuss your concerns with an allergy doctor. However if you are experiencing pain or visual changes, you should promptly contact an ophthalmologist or go to the nearest emergency department.