I had the same trouble and also my eye watered badly when I went outdoors in the cold or wind, tears streamed down my face. This went on for ages and the corner of my eye itched. to cut a long story short Specialist at Hospital said I did not have a blocked tear duct but a narrowing of the duct right in the corner .He numbed it and then an anaesthetic injection and then a slight snick with a scalpel. Job done. A 5 minute operation. Since then the itch has gone,no tears and no blurry vision in that eye which I had before cos it was always watering. Perhaps you have the same problem Worth getting it checked out.