If I eliminate all cosmetics to see if they are cause of bloodshot eyes, how soon will I see improvement?

My eyes have had a pink hue and bloodshot lines for many months. Opthamologist ruled out disease/infection and dry eye, and thinks it must be environmental. I don't have any other allergy symptoms (itching, etc.), just pink/red eyes that feel dry and tired. I get enough sleep, look away from computer screen frequently, etc. Doc recommended I eliminate ALL cosmetics on or around my face -- yikes. How long should it take before I either see improvement or know that cosmetics are not the problem? I have also had rosacea in the past, and when I did, it affected my eyes. But I currently have no rosacea symptoms. Could the rosaceo be recurring ONLY in my eyes? Other ideas?