Glasses can NOT correct vision.
More Info: Glasses will correct sight and vision while wearing them, but do not correct the cause of vision problems. As a result, taking off the glasses will result in the same nearsightedness or farsightedness that caused a prescription for glasses.
What Do Glasses Do?
If a doctor prescribes glasses, then vision is not normal for any reason. Depending on the cause of vision problems, the type of glasses given by a doctor will vary. Regardless of the particular problem, glasses are used to help improve vision by adjusting the refraction of light.
Correcting Vision While Wearing Glasses
Glasses do not actually correct the problem with the eyes. Problems with vision are caused by the shape of the eyes and the way the brain is able to interpret the refraction of light in the eyes. Instead of correcting the particular problem with shape, glasses are curved to adjust the refraction of light. The result is that vision is improved as long as glasses are worn.
Problems with vision stem from the shape of the eyes and the refraction of light. If the doctor determines that eyes are nearsighted, then the shape of the eyes is elongated. When the eyes are elongated, the light will not reach the retina and causes a distortion in distance vision.
Farsightedness occurs when the eyes are more rounded and pushed forward. Vision near the eyes is difficult to see due to the light refracting beyond the retina and distorting vision in front of the face.
Regardless of the particular vision problem, glasses are designed to refocus the light for better vision. The shape of the glasses will curve to adjust the way the light enters the eyes. When the light is adjusted, vision clarifies and ultimately is corrected by the glasses. Since glasses do not change the shape of the eyes, it will only correct vision when wearing the glasses.