The sides of the glasses should be adjusted to the shape of the face so that no pressure can be felt on the temples. Often, such pressing at the temples is misunderstood to mean that the glasses are sitting properly. Optimally-fitted sides should only cause a slight pressure behind the ear to keep the weight of the glasses from bearing down on the nose. However, if the glasses are too tight, the sides move upwards on the sides of the head and the eyeglass frames slide down the nose.
By the way, in certain situations, the sides of plastic eyeglass frames can deform slightly due to changes in temperature caused by the weather. If this causes discomfort, your eye care professional can get the glasses back to their original shape easily.
Tips for active sports fans: Silicone tips and covers for metal frames are water-repellent and ensure a tight grip and optimum fit even during heavy sweating.