Two kinds of “expired” to distinguish In real life, many people will always have a bottle of eye drops, when the eyes are uncomfortable, it can be very convenient to use. And those who work every day on the computer, but also without eye drops. Eye drops are often used, but many people will confuse the difference between the shelf life after opening the bottle and the shelf life before opening the bottle. After the eye drops are opened, they may be used for a year and a half, and often end up costing more than they are worth. Obviously, there is a difference between the shelf life before and after the opening of the bottle, this reason is actually very simple, but many people use it negligently. Eye drops are best used up within 4 weeks of opening It is understood that the country is usually recommended that eye drops are safer to use within 4 weeks of opening. Foreign countries are gradually turning to promote disposable eye drops to reduce the harm caused by the use of expired eye drops. According to Zhou Hongjian experts, eye drops should be opened within a month after the drops, otherwise the liquid will deteriorate or lose its effectiveness, and not used up to throw away. Dr. Zhou also pointed out that the shelf life of eye drops generally refers to the time that can be preserved in a cool, dry environment and without opening. Opened eye drops and air contact may be contaminated, deterioration, and eye drops contain preservatives, opened a month after the eye drops in which the active ingredients may have evaporated, and too frequent use will inevitably cause damage to the eyes. Once opened, eye drops and ointments used for too long are likely to lead to eye diseases, such as corneal ulcers, eye lesions, eye inflammation, etc. The way to preserve eye drops In addition to not using them for more than 4 weeks after opening, the preservation of eye drops is also something worth noting. Eye drops usually need to avoid direct sunlight, high temperature, humid environment, should be placed in a cool, light-free place. If the weather is hot, you can put it in the refrigerator where the temperature is kept at 4℃. Secondly, the cap should be tightened after each use to reduce the chance of contamination and leakage of the solution. In addition, you can also judge the preservation of eye drops by observation. If the eye drops are no longer clear and transparent, or if they have an odor, particles as well as become cloudy and appear cotton wool-like precipitates, it means that they have deteriorated and should not be used again. Another option for eye drops Since eye drops in general cannot be stored for a long time after opening, it is a bit painful for many people who use eye drops to throw them away in 4 weeks. Therefore, it is recommended that such people choose small, preservative-free eye drops. This small (0.4 ml, etc.) eye drops do not contain preservatives, but the price is slightly higher and the number of uses is less. In addition, since these eye drops do not have caps, please use them within a few hours after opening and be careful to avoid contaminating the bottle.