If your prescription has chnaged, then your old glasses are no longer good for you. In this case, you can take your old glasses to any optical store to ask them replace the lenses with your current prescription if you do like the frames. If your prescription is valid and the frames are out of date, you can just buy new frames to fit your lenses. In this way, you old glassses can be reused and it can help you save much money on new glasses.
lololo... you must wearing eyeglasses for many years. You can prepare a cabinet to keep your old eyeglasses. It can decorate your house to show them to others. Or just keep them as a backup even though you not wear it right now. If you don't want to throw them away and want make full use of them, you can donate your old eyeglasses to charity that will help some poor people get clear vision.
As the eyeglasses are updated due to our deeper prescription or some fashionable and functional new arrivals of eyeglasses, we always get new glasses every other year or more. As a result, you may have enough pairs of old glasses to decorate your room or living room in your style. White-washed walls, wooden floors and the shutters combined with the various glasses posing like a butterfly may be fascinating. Besides that, it will be very kind of your to donate your old glasses to some charities like World Vision Overseas or KODAK Lens to recycle the glasses by adjusting the nose pads and they do accept varifocals. In addition, they do appreciate your kindness.