Here is some info dealing with familiar eye problems which may result in you having to need prescription spectacles
Myopia – Also known as short sightedness, near sightedness
Nearsighted people generally visualize fine up close, but not at a distance. Distant objects appear blurred, whilst close objects are in focus.
DESCRIPTION
The eyeball 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 distance at which the Shortsighted can focus clearly.
SOLUTION
Myopia can be corrected with a concave lens system which is thin in the centre and thicker at the periphery. This type of lens pushes the focus back onto the retina and restores good vision at any distance.
HYPEROPIA – Long sightedness, far sightedness
Farsighted people view much better at a distance compared with close up. Even though distant objects appear 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 thin at the boundary and thick in the centre. 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 appreciate the contrasts between horizontal, vertical and diagonal lines in the same style as the rest of us.
Astigmatism is always accompanied by other visual impairment, such as Myopia, hyperopia and Presbyopia.
DESCRIPTION
Astigmatism is normally caused by an irregularly-shaped cornea that is slightly oval, as opposed to round, and oblong instead of spherical.
SOLUTION
Astigmatism can usually be corrected with a cylindrical lens system whose curvature offsets the corneal irregularity.
