You can tell whether a person is nearsighted or farsighted by looking at the width of the face through their glasses. If the person's face appears narrower through the glasses (Fig. ), is the person farsighted or nearsighted?
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Lens thicker at the Centre than at the edges is a converging lens. Lens thinner at the Centre than at the edges is a diverging lens. A diverging lens always forms a virtual image that will be upright and smaller than the object, regardless of the position of the object.
Normal eye focuses light and produces a sharp image, just like a camera. The cornea-lens system focuses light onto the back surface of the eye called retina. A person, who can see distant objects clearly but cannot focus on near objects is farsighted. Farsightedness is corrected with a converging lens. A person, who can see near objects clearly but cannot focus on distant objects is nearsighted and is corrected with a diverging lens.