Some people think their eyeglasses and sunglasses should last quite a long time. In fact, many times we see loads of people damaging their eyeglasses without realizing they do something wrong. The most frequently we can see people wearing glasses in their head (used as hair accessory) or on forehead (usually people with reading glasses). Eyeglasses will stretch to the sides and in better case you will just have twisted frame, in worse scenario the flexi joints may break after some time. Your eyeglasses will also be  exposed to more stretch if you put on and take off your glasses only with one hand; its one side will be strained more than the other and especially reading glasses which people manipulate with many times a day can be damaged quite soon.

If you want your eyeglasses and sunglasses look polished for a long time, be careful with cosmetic products with alcohol content you use on your face and hair (after-shave products, hair sprays etc.). They leave some residuum on surface of the eyewear and can change the color of temples or damage antireflective coating (hair sprays).