It is hard to say. In fact, it depends on yourself. If you find you are nearsighted and start to wear eyeglasses. And you often keep some bad habit such as working with computer without break or reading in dim light in long time etc. This make it inevitable that your eyesight will get worse. Or you use eyeglasses properly or struggle on without wearing eyeglasses, in addition to keep good habit of using eyes. For example. Keep doing eye exercise every or keep good posture when reading and writing etc. It is likely to improve eyesight or at least slow the rate of short-sighted change.
Glasses won't make your vision better or worse. They just help you see better. Your vision get worse when you overuse your eyes and make them tired. Eye fatigue is one of the leading cause of vision problems. So to prevent your vision getting worse, you should use your eyes in a right way and don't make them tired. If you have strong prescription, you need to wear glasses all the time, otherwise your vision will become worse because when you see things clearly with no glasses on, you will strain your eyes. If you have low prescription, you can wear glasses when needed.
If you got serious myopia, I kindly suggest you to wear eyeglasses which will not make your vision worsen. However, if your myopia is not serious so that it is not necessary for you to wear. You can take some eye excise to help the recovery of your vision naturally. Wearing glasses can't cause eyesight serious, but your life style do. So, taking care of your eyes and spend less time on computer or TV screen. Hope this can help you.