When I get red itchy eyes it is usually an allergy or a reaction to a chemical solvent. The first step is to wash my face and hands throughly with a borax solution. It often takes repeated washings . Then I search for the cause - machine oil, new furniture, glossy magazine covers, cleansing agents in cupboards, dust buildup, molds in damp places and more. If you are getting cayenne on your hands it could easily be carried to your face, especially if you rub your eyes.