Wow, there are many reasons that make you want another pair of glasses. For example, if you think your glasses are too old, you can change them.
If you think you need different types of glasses to match your clothes or different occasions, you can fill yourself more glasses. But maybe the most important is that the prescription is too strong or too low for you as your eye vision changes. So, try to tell whether it is not fit for you anymore.
There are some tips which will help you. If the glasses are too strong, when you watch with this pair of glasses, it is hazy. And you are not look at the right place or thing. The second is it makes your head vertigo when you wear it. If the prescription is too low, you can't see the things clearly. So, you can go to the eye doctor to have a test with your eye vision. Personally, I think people wearing glasses should go to test the eye vision at least half a year once.
If your vision is blur with present glasses or cannot see as well as you used to, it is may the time you should get a new pair of glasses. Some eye disease may also cause such kind of symptoms, so you should make it clear firstly. It is better to get your eyes checked once a year or every six months.There are different symptoms associated with different ocular problems, so it is important to recognize them and to ask the doctor for professional advice. Normally, all the optical shops are offering vision test for free.