Prescriptions for eyeglasses include a variety of details to be fully customised to each individual.
Sphere (SPH): indicates the amount of lens power, measured in dioptres (D), prescribed to correct short-sightedness (indicated with minus sign –) or long-sightedness (indicated with plus sign +). It is ideally determined to the nearest 0.25D.
Cylinder (CYL): indicates the amount of lens power for astigmatism.
Axis: indicates the orientation of the astigmatism. It is a number anywhere between 0 and 180 degrees.
Near Addition (ADD): indicates the additional refractive power to be combined, or added, to the distance power to achieve the ideal near power.
Prism: indicates the amount of prismatic power, measured in prism dioptres, prescribed to compensate for eye alignment problems.
Pupillary Distance (PD) or Interpupillary Distance (IPD): indicates the distance between pupil centres.