Your eyesight is determined during an eye test and generally speaking the higher your prescription the worse your eyesight will be. The optician will determine this using many different techniques and at the end of the eye test you will be given a prescription whose numbers relate to the power of lens that is required to make your vision perfect.
Explaining Your Eyesight:
The prescription of your eye is derived from the power of the cornea (outer clear part of your eye) and the lens inside your eye. The eye sees all objects as differing amounts of light and contrast. Perfect eyesight occurs when the light/image entering your eye is focussed exactly onto the retina at the back of your eye. The retina is the part of the eye which collects and organises all the information (light) entering your eye. It then sends this information to the brain via the optic nerve where the processing takes place for us to see. If the light is focussed either in front or behind the retina, then your vision is blurred and hence you will need contact lenses, glasses or laser eye surgery.
- If the power of your eye (cornea and lens) is too powerful, then the light entering your eye will fall in front of your retina and this is called myopia. Such people are said to be short sighted.
- If the power of your eye is too weak then the light entering your eye will fall behind your retina and this is called hypermetropia. Such people are said to be long sighted.
- Astigmatism is caused by the shape of your eye being different in one direction compared with the other, resulting in blurred vision. Special lenses are needed to correct this eye sight problem.
Having perfect eyesight is something most people take for granted but for a large percentage of the population this is not the case. For these people they are left with no option but to wear spectacles, contact lenses or consider laser eye surgery.