The functional advantages of contact lenses over glasses can be felt in areas like sports, working in humid conditions and also in occupations where glasses can be very inconvenient and may not be compatible when using equipment like special headgears. Contact lenses also offer aesthetic advantages as they do not alter the image of the person wearing it. When contact lenses are worn correctly on the cornea of the eye, the vision is very similar to the natural vision. The objects are seen in the right size and position without any kind of distortion of the image. When glasses are worn, the distance between the glasses and the eye vary making the objects appear smaller or larger than the actual size, position etc. Contact lenses are not altered by bodily movements, as in the case of sports or similar kind of activities. They remain stable providing stable and clear vision to the wearer. When glasses are worn, the vision is unstable while moving or running, in turn affecting the performance of the wearer. Contact lenses provide a better and wider peripheral vision than the glasses. Contact lenses move with the movement of the eyes and the wearer always looks through the clearest part of the lens called the optic zone. When glasses are worn, it blocks the peripheral vision. When the eyes move to the sides, the sight is far from the optic center leading to distorted and blurred vision. Contact lenses do not steam up due to body heat or perspiration. They also neither fog when exposed to cold weather nor get splattered in the rain. Glasses on the other hand fog up and the wearer cannot see completely during rain pour. Contact lenses do not leave marks on the nose and are very comfortable to wear. No pressure is felt on the ears, temple, or nose unlike the glasses. Also glasses slide down from the nose during perspiration. As told before, contact lenses do not alter the appearance of the person. They are boon for children who are often picked up at school for wearing glasses. Contact lenses provide both physical and psychological comfort to the wearer. Also, after cataract operations, contact lenses provide the necessary protection more than the glasses. Contact lenses offer adequate correction when the visual acuity of the eyes are more than 2.5 diopters, which is not possible with the glasses.