Before going to bed can drop eye drops, general eye drops are more convenient to use during the day, because at any time may be adjusted according to the number of times, such as three times a day or point to eight times a day, point more frequently, but also only during the day to use eye drops. Because the night to sleep, after closing the eyes, open the eyes to the next day, the middle can not point again drops, which is very inconvenient. So at night is generally used are more eye ointment or gel, because these drugs maintain a longer time, such as a sleep at night may be eight hours, the sustained effect of some longer. Eye drops because after dropping into the eye, most can flow away with the tear duct. Even if the pressure on the tear sac area, the eye surface absorption will dissipate in the short term, while the cream is an oily adherent, it will remain in the eye for a longer period of time, and the effectiveness of the drug will increase.