Common refractive disorders of the eye such as are measured in units called diopters. Diopters represent the amount of correction you need to normalize your vision. The more nearsighted, farsighted, or astigmatic you are, the higher your prescription in diopters.
Your prescription is composed of three numbers:
-5.00 -1.50 x 180 represents a typical prescription
The first number -5.00 identifies your degree of nearsightedness or farsightedness. The sign identifies whether you are nearsighted (- sign) or farsighted (+ sign).
The second number -1.50 identifies your degree of astigmatism. The number can be written either with a (+ sign) or a (- sign).
The third number 180 identifies the axis, which indicates the direction of your astigmatism. An axis of 180 degrees, for example, means the astigmatism is horizontal.
Therefore, a prescription of -5.00 -1.50 x 180 indicates that the patient is moderately nearsighted, with a moderate degree of astigmatism in a horizontal direction.