Here is some info about some of the common eye problems which may cause you to need prescription eyeglasses

Myopia - Also known as short sightedness, near sightedness

Myopic people visualize well up close, but not at a distance. Distant objects seem blurred, whilst near objects are in focus.

DESCRIPTION

The eye ball is longer than usual, making the eye "too powerful." The image is focused at a point in front of the retina. The higher the degree of myopia, the shorter the distance at which the Myopic can visualise clearly.

SOLUTION

Myopia can be corrected using a concave lens which is thin in the center and thicker at the edge. This type of lens pushes the focus back onto the retina and restores good vision at any distance.

HYPEROPIA - Also known as long sightedness, far sightedness

Farsighted people visualize much better at a distance than close up. Even though distant objects are properly focused, the accommodation required to focus on close objects causes eyestrain.

DESCRIPTION

The eye ball is shorter than normal which means the eye is not powerful enough. The eye is said to be "too short" and the image is focused behind the retina.

SOLUTION

Hyperopia is corrected with the use of a convex lens that is thinner at the edge and thicker in the center. This type of lens brings the focus forward to the retina.

ASTIGMATISM

People with astigmatism have poor close and distant vision. They do not appreciate the contrasts between horizontal, vertical and diagonal lines in the same manner as the rest of us.

Astigmatism is always accompanied by another visual impairment, such as Myopia, hyperopia and Presbyopia.

DESCRIPTION

Astigmatism is typically due to an irregularly-shaped cornea which is slightly oval, as opposed to round, and oblong rather than spherical.

SOLUTION

Astigmatism can usually be corrected with a cylindrical lens whose curvature offsets the corneal irregularity.