If your eyeglasses are made of plastic frames, you can adjust it by yourself. First, you can use hair drier to blowing your eyeglasses frames till about 10 to 15 minutes. By doing this, It will make the plastic frame softer than usual. Then, you can adjust your eyeglasses frame as you want. Then, clean the glasses and wait it cool. However, if your eyeglasses are made of metal frame, you shall have an optician to do it. Or you may have to buy a new pair of eyeglasses frame instead of the tight pair.
It is easy for you to do to make adjust your glasses which are too tight. You could just find the screw to adjust the nose pad position to make it not that tight. About the points like the frames of the eyeglasses, you could also use the screw to adjust it. It will be so useful and easy. You could just try it on yourself.