You Need Eyeglasses - Why?
Here is some info about general eye troubles which may result in you having to need prescription spectacles
Myopia - Also known as short sightedness, near sightedness
Nearsighted people can visualize fine up close, but not at a distance. Distant objects are blurred, while nearby objects are in focus.
DESCRIPTION
The eyeball 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 closer the distance at which the Shortsighted can see clearly.
SOLUTION
Myopia can be corrected with a concave lens which is thinner in the center and thicker at the edge. This type of lens system pushes the focus back onto the retina and restores good vision at any distance.
HYPEROPIA - May be known by the terms long sightedness, far sightedness
Farsighted people see much better at a distance than close up. Even though distant objects seem properly focused, the accommodation required to focus on close objects causes eyestrain.
DESCRIPTION
The eyeball 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 a convex lens system that is thin at the border and thicker in the center. This type of lens system brings the focus forward to the retina.
ASTIGMATISM
People with astigmatism have poor nearby and distant vision. They do not sense the contrasts between horizontal, vertical and diagonal lines in the same fashion likened to those with typical eyes.
Astigmatism is always accompanied by other visual impairment, such as Myopia, hyperopia and Presbyopia.
DESCRIPTION
Astigmatism is usually due to an irregularly-shaped cornea that is slightly oval, rather than round, and oblong as opposed to spherical.
SOLUTION
Astigmatism can be corrected using a cylindrical lens whose curvature offsets the corneal irregularity.
