Shortsightedness occurs when the eyeball is longer than normal along the horizontal axis from the lens to the retina. The eye can still focus on near objects, but parallel rays from the distant objects can no longer be focused onto the retina and are brought to a focus in front of the retina forming a blurred image. The correction for this defect is to wear suitable concave lenses to diverge the rays from distant objects before they reach the eye. These rays can then be focused onto the retina and a clear image formed.
Without glasses shortsighted people can focus objects clearly only when they are very close to the eye.A person suffering from long-sightedness can see distant objects clearly but cannot see near objects clearly. The near point of the eye may be more than a meter away so that ordinary reading is not possible. This defect arises from a shortening of the eyeball along the horizontal axis from the lens to the retina. Rays from a near object are brought to a focus behind the retina. This defect can be corrected by wearing suitable convex lenses so that the rays from the near object are made to converge and focus upon the retina.
Without glasses shortsighted people can focus objects clearly only when they are very close to the eye.A person suffering from long-sightedness can see distant objects clearly but cannot see near objects clearly. The near point of the eye may be more than a meter away so that ordinary reading is not possible. This defect arises from a shortening of the eyeball along the horizontal axis from the lens to the retina. Rays from a near object are brought to a focus behind the retina. This defect can be corrected by wearing suitable convex lenses so that the rays from the near object are made to converge and focus upon the retina.
