YOUR PRESCRIPTION

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hyperopia and presbyopia) are measured in units called 'diopters'. Diopters represent the amount of correction needed in corrective lenses to normalize vision. The more nearsighted or farsighted you are, the higher your prescription in diopters. 

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Visual refractive disorders of the eye (e.g. myopia, astigmatism,

Your prescription is written in three numbers: 

For example, -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. This means that the cornea is shaped like a football with one steap meridian. If there is no astigmatism, it is shaped like a basketball.

The third number (180) is the axis, which indicates the direction of your astigmatism. An axis of 180 degrees, for example, means the steep axis is vertical. 

Therefore, -5.00 -1.50 x 180 means that the patient is moderately nearsighted, with a moderate degree of astigmatism with the steep axis in the vertical direction. 

Most excimer laser studies have found the "typical" laser patient to be 30 to 35 years old, with a prescription between -3.00 and -4.00 diopters of myopia with less than 1.00 diopter of astigmatism.