You Need Spectacles – Why?
Here is some information about some of the familiar eye troubles for which you may need prescription glasses
Myopia – Short sightedness, near sightedness
Shortsighted people visualize well up close, but not at a distance. Distant objects appear blurred, while close objects are in focus.
DESCRIPTION
The eye ball is longer than usual, making the eye "too powerful." The image is focused at a point ahead of the retina. The greater the degree of myopia, the closer the point at which the Shortsighted can view clearly.
SOLUTION
Myopia can be corrected with the use of a concave lens which is thinner in the center and thick 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 focus much better at a distance compared to close up. Although distant objects seem properly focused, the accommodation required to focus on nearby 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 the use of a convex lens system which is thinner at the boundary and thick in the centre. This type of lens 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 as the rest of us.
Astigmatism is always accompanied by an additional visual impairment, such as Myopia, hyperopia and Presbyopia.
DESCRIPTION
Astigmatism is typically a result of an irregularly-shaped cornea which is slightly oval, rather than round, and oblong instead of spherical.
SOLUTION
Astigmatism can usually be corrected with the use of a cylindrical lens whose curvature offsets the corneal irregularity.
