Understanding Your Prescription

When your eyes are tested, your Optometrist will give you a prescription which looks something like this:

SPH (short for sphere) indicates the roundness of the cornea. A minus (-) sign before the digit means you are short-sighted and the digit expresses the degree of short-sightedness. A plus sign (+) indicates long-sightedness.

CYL (short for cylinder) indicates the irregularity of the corneal shape, the greater the digit the more elongated the cornea (like a rugby ball compared to a football). This represents astigmatism which can be either longsighted (+ sign) or short sighted (- sign).

AXIS refers to the angle of the astigmatism from 0 to 180 degrees.

PRI AND BAS (short for prism and base) relate to a special prism lens used for the correction of squint.

ADD This is a plus prescription you may need to help you read either with bifocals or varifocal lenses