Understanding Your Prescription

Laser Institute of Michigan

Optical prescriptions appear as a series of numbers that represent the refraction needed to give you your best corrected vision. It is measured in units of a diopter and the series is displayed as +/- sphere +/- cylinder x axis. An optical prescription typically appears as follows:

  • D.V., stands for Distance Vision, and pertains to the additional power that is needed to enable the eyes to focus on objects that are far away.
  • N.V., stands for Near Vision, shows the additional positive power that is needed to enable the eyes to focus for reading or close work. If a reading addition is stated, this means different prescriptions are needed for reading and for distance.
  • O.D. is information pertaining to the right eye.
  • O.S. is information pertaining to the left eye.

Spherical refers to the amount of nearsightedness or farsightedness that is present. If the sphere number is negative, then the patient is nearsighted. If it is positive, then the patient is farsighted. The larger the number, the stronger the correction will be.  If your sphere number is zero, it is referred to as “plano” or “PL” meaning no nearsightedness or farsightedness exists.

Cylindrical refers to the amount of astigmatism. This will be left blank if no astigmatism exists. It can also be expressed as either positive or negative. This will be left blank if no astigmatism exists.

Axis refers to the direction of the Astigmatism (from 0-180 degrees) and is the angle at which the lens is set into the frame.

Prism is the correction needed (if any) to align the eyes, so that they are looking straight and working well together.  A prism is a lens that bends the path of light without altering its focus.

Near VA, stands for Near Visual Acuity, and represents the smallest sized print that can be read with the prescription.

The doctors and staff at Fraser Eye Care Center and the Eye Care Center of Port Huron will be happy to discuss your prescription with you and answer any questions you may have about the latest technologies for improving your vision.