Greetings Sir/Madam. I m glad i can help you overcome your discomfort. It s unfortunate that you have been suffering from Itching past 15 years(as per your details) & was on certain medication that doesn t seems to get relieved of your discomfort. But you didn t mention that whether medication was taken with doctor prescription. If did so without prescription, so sad that your simple problem could have become a more complex serious problem in these long years. My opinion is that it could have been a simple allergy, dry eyes, infection which could have been cured once you would have visited a doctor. But now this seemingly minor problem could have become a potentially vision-threatening diseases. the problem can range from a number of ocular surface diseases viz., allergies, dry eye syndrome, infection of glands of eyes, etc., A complete history, review of systems and examination can help differentiate among these above reasons. Treatment are based on the condition you have & also nature of your body condition with any other associated systemic problem. My sincere advise is first get yourself examined by a Ophthalmologist(Eye doctor) & follow his instruction to prevent further deterioration of your problem. & Finally Note: Finally it s just a guidance. Not a definitive treatment as i haven t seen you personally. You ve to realize that these are temporary remedies. We don t know what your exact condition is unless we see you personally. A doctor after personally examining you could help . Hope it helped you.