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Understanding your Prescription

Each time your visit an optometrist, you come back with a detailed prescription slip. Deciphering your prescriptions correctly especially while ordering your eyeglasses may look tricky with all the abbreviated terms and series of + & - numbers. This all-inclusive guide will help you read your prescriptions in an easy manner and understand all the terms in detail. Let’s start with the basics -

  • O.D. stands for Oculus Dexter or Right Eye
  • O.S. stands for Oculus Sinister or Left Eye
  • DV stands for Distant Vision
  • NV stands for Near Vision
  • + indicates long-sightedness or Hyperopia
  • - indicates correct near-sightedness or Myopia
Now that you’ve understood the basics,
let begin decoding your prescription terms
  • Sphere (SPH)
    Sphere or SPH is the power of the lens required to correct a single vision defect. This can be for myopia and hyperopia. It is measured in Dioptres. The prescription can differ for both the eyes.
  • Cylinder (CYL)
    Cylinder power indicates that your eyes are not perfectly sphere in shape. If you have some numbers in your CYL column of your prescription, you will require eyeglasses to correct astigmatism.
  • Axis
    Axis reflects the exact orientation of your astigmatism. It is always present along with your CYL prescriptions. If your prescription holds a CYL value and no axis or vice versa, it is incomplete.
  • ADD (Addition)
    Add or Near Addition power is added on the lower part of the multifocal/bifocal lenses to correct presbyopia. This helps one in performing close-up tasks with ease.
  • Pupillary Distance (PD)
    Pupillary distance is an important measurement from the center of one eye to the center of another. This is used to mark the exact optical center in your lenses which further helps to view things properly and without any eye strain.
Sphere (SPH)
  •  
  • Sphere (SPH)

    Sphere (SPH)

    Spherical error, or overall power of lens is the basic part of your prescription. A (+) indicates farsightedness and a (-) indicates nearsightedness.
  • Cylinder (CYL)

    Cylinder (CYL)

    Cylinder value indicates astigmatisms or perpetually blurry vision.
  • Axis

    Axis

    To make your vision impeccable, we use a degree between 1 and 180 to tell us your astigmatism axis orientation.
  • ADD (Addition)

    Axis

    This number is sometimes written NV for Near Vision and is used in multifocal lenses and readers.
  • Right Eye (OD) *
  • Left Eye (OS) *
  • Additional Information
  • Pupillary Distance (PD): *
  • Corrects Myopia & Hyperopia
  • Ranges from 0.00 to +/- 20.00 D
  • Higher prescription means high degree myopia/hyperopia
Cylinder (CYL)
  •  
  • Sphere (SPH)

    Sphere (SPH)

    Spherical error, or overall power of lens is the basic part of your prescription. A (+) indicates farsightedness and a (-) indicates nearsightedness.
  • Cylinder (CYL)

    Cylinder (CYL)

    Cylinder value indicates astigmatisms or perpetually blurry vision.
  • Axis

    Axis

    To make your vision impeccable, we use a degree between 1 and 180 to tell us your astigmatism axis orientation.
  • ADD (Addition)

    Axis

    This number is sometimes written NV for Near Vision and is used in multifocal lenses and readers.
  • Right Eye (OD) *
  • Left Eye (OS) *
  • Additional Information
  • Pupillary Distance (PD): *
  • Corrects Astigmatism
  • Ranges from 0.00 to +/- 4.00 D
  • Higher prescription means high degree astigmatism
Axis
  •  
  • Sphere (SPH)

    Sphere (SPH)

    Spherical error, or overall power of lens is the basic part of your prescription. A (+) indicates farsightedness and a (-) indicates nearsightedness.
  • Cylinder (CYL)

    Cylinder (CYL)

    Cylinder value indicates astigmatisms or perpetually blurry vision.
  • Axis

    Axis

    To make your vision impeccable, we use a degree between 1 and 180 to tell us your astigmatism axis orientation.
  • ADD (Addition)

    Axis

    This number is sometimes written NV for Near Vision and is used in multifocal lenses and readers.
  • Right Eye (OD) *
  • Left Eye (OS) *
  • Additional Information
  • Pupillary Distance (PD): *
  • Indicates degree/direction of astigmatism
  • Ranges from 0 to 180 Degrees
  • Always present along with Cylinder Value
ADD (Addition)
  •  
  • Sphere (SPH)

    Sphere (SPH)

    Spherical error, or overall power of lens is the basic part of your prescription. A (+) indicates farsightedness and a (-) indicates nearsightedness.
  • Cylinder (CYL)

    Cylinder (CYL)

    Cylinder value indicates astigmatisms or perpetually blurry vision.
  • Axis

    Axis

    To make your vision impeccable, we use a degree between 1 and 180 to tell us your astigmatism axis orientation.
  • ADD (Addition)

    Axis

    This number is sometimes written NV for Near Vision and is used in multifocal lenses and readers.
  • Right Eye (OD) *
  • Left Eye (OS) *
  • Additional Information
  • Pupillary Distance (PD): *
  • Indicates the additional reading power
  • Used in bifocals, progressives and reading glasses
  • Added at the bottom half of the lens for people with presbyopia
Pupillary Distance (PD)
  •  
  • Sphere (SPH)

    Sphere (SPH)

    Spherical error, or overall power of lens is the basic part of your prescription. A (+) indicates farsightedness and a (-) indicates nearsightedness.
  • Cylinder (CYL)

    Cylinder (CYL)

    Cylinder value indicates astigmatisms or perpetually blurry vision.
  • Axis

    Axis

    To make your vision impeccable, we use a degree between 1 and 180 to tell us your astigmatism axis orientation.
  • ADD (Addition)

    Axis

    This number is sometimes written NV for Near Vision and is used in multifocal lenses and readers.
  • Right Eye (OD) *
  • Left Eye (OS) *
  • Additional Information
  • Pupillary Distance (PD): *
  • Distance between the centers of two pupils
  • Ranges from 50 to 70 mm
  • Incorrect PD value can cause eye strain & visual distortion
Here are some additional prescription examples

Astigmatism

Prescription shows astigmatism with additional CYL & Axis values & no inputs for ADD column

Single Vision - Myopia

Negative power indicates near sightedness. No CYL & axis values present.

Astigmatism

Prescription shows astigmatism with CYL power & Axis degree.

Single Vision – Myopia

SPH values have - 5.5 in each eye indicating Myopia

Bifocal / Progressive

NV power is added to the prescription below SPH making bifocal/progressive the right choice.

Bifocal / Progressive

ADD (near) power is added to the prescription along with SPH in O.D. & CYL & Axis in O.S.

Bifocal / Progressive

ADD value of +2.25 confirms presbyopia. Bifocals/progressives are the suitable choice.

Bifocal / Progressive

SPH in O.D., CYL in O.S. & ADD value directs to Presbyopia. Progressives/ bifocals are required to correct vision.
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