What are the ways that eyeglasses or contact lenses work to correct your vision?

Focus light: If the only problem with your vision is an uncorrected need for classes, then your eye has a focal point off the retina (the film at the back of the eye). The ;job of glasses and contacts is to readjust that focal point with its peak on the light receptive elements of the retina so there is a clear image. This compensates for your eyes inability to do this.