My doctor said I had a block in my right eye. With your head tilted back, reach across the nose with the hand not holding the bottle and push down and in where the two lids come together to close the clear duct. Using the other hand, put the drop in the eye, and gently close the eye to avoid squeezing out the drop. Keep the pressure on the tear duct for three minutes. That is the perfect way.
Few people are that rigorous.
I especially recommend blocking the duct before using beta blockers and Alphagan. I thought I was having a side effect from Alphagan. Actually, the problem was related to undiagnosed Hashimoto's Thyroiditis. Anyway, make sure you consider other stuff in your health history. I have Reiter's syndrome and so do my two daughters, ages two months and four years.