Hello, first bifocal glasses are prescription lenses to change the eye's focus. But they are still not perfect. For example, usually they can fit well, but sometimes they will slip out of position so that the focus changes being created are out of position also, which can affect your vision. What's more, some problems can also be caused by bifocal glasses, such as headaches, visual dizziness and image jump.
The bifocal glasses are really perfect for the wearers to see both the things far away and near. However, the wearer will not get adapted to changing the things from far places to the near parts. The eyes may feel a little dizzy. That is why a lot of people now use to wear the progressive eyeglasses which have more prescription lenses to avoid the dizzy eyes.
Well, yes, bifocal glasses have some side effects even if they are very wonderful. As we know that bifocal glasses can achieve the most favorable balance between near vision and distant vision all in one convenient pair of glasses. You should know that it is very beneficial to someone who need both near and farsighted vision aids. But on the other hand, when you wear them in the first time, it will take some time for your eyes to be accustomed to them, and sometimes, it can just make you have high eye pressure, leading to eye strain. Sometimes, eye pain may occur too. At that moment, you may need to have some eye drops to relieve your situation.