At the end of your eye test, you'll be given a prescription which will usually be valid for two years. The different numbers and abbreviations it contains detail the condition of your eyes and the prescription required.
This refers to the degree of long and short sight that's present in your vision and the power of the lenses required to correct this.
This relates to any astigmatism that is present in your eyes. Astigmatism is a common condition which is caused when the eye is not perfectly spherical and it results in blurred vision as the eye is unable to focus the light entering the eye on the retina.
This refers to the orientation of the cylinder (from 0-180 degrees) and is the angle at which the cylindrical power in your lens must be positioned.
This is the correction needed to align the eyes, overcoming an eye muscle weakness and ensuring that both look straight and work well together. A prism is a lens that bends the path of light without altering focus.
This is the added magnifying power in the lower part of a multi-focal lens and it's used to correct presbyopia (long sightedness).