Breaking Down the Numbers: Understanding Your Eyeglass Prescription

If you have been wearing vision-correcting eyeglasses, you may have noticed that your prescription comprises a series of numbers and abbreviations. While it may seem like a complex code, understanding your eyeglass prescription is essential. This will ensure you get the right lenses to correct your vision. Below is a breakdown of the numbers and an explanation of what each component of your eyeglass prescription means. It will help you make informed decisions about your vision correction.



Sphere (SPH)


The sphere is typically represented by the abbreviation SPH on your prescription. It indicates the lens power needed to correct:


  • Nearsightedness (represented by a negative number)

  • Farsightedness (represented by a positive number)


The sphere measurement is given in diopters (D). It indicates the strength of the lens required to bring your vision to normal.



Cylinder (CYL)


The cylinder measurement, denoted as CYL, is relevant for individuals with astigmatism. This eye anomaly occurs when the lens or cornea is irregularly shaped. This results in blurred or distorted vision. The cylinder measurement represents the lens power needed to correct astigmatism. It is also given in diopters. This section of your prescription will be left blank if you are not astigmatic.






The axis is expressed in degrees. It works in conjunction with the cylinder measurement for astigmatism correction. It indicates the orientation of the cylinder lens needed to align with the astigmatism axis on your eye. The axis is crucial for ensuring that the corrective lens is positioned correctly. It helps provide optimal vision correction.





The add, or near vision prescription, is for those who require bifocal or progressive lenses. This is an age-related condition that affects the ability to focus on close objects. The add measurement represents the additional lens power needed for reading or other close-up tasks and is usually denoted by ADD on the prescription.





In some cases, your eyeglass prescription may include a prism measurement. A prism corrects eye alignment issues, such as double vision or eye muscle imbalances. The prism measurement is indicated in prism diopters. It determines the direction and amount of correction needed to align the eyes properly.



Pupillary Distance (PD)


The pupillary distance (PD) is not always included in the prescription. It is an essential measurement for accurately fitting your lenses. The PD represents the distance between the centers of your pupils. This helps align the optical center of the lens with your eyes. It ensures you have clear and comfortable vision through the lenses.





Understanding your eyeglass prescription is crucial. It ensures you receive the correct lenses to address your vision needs. The various components of your prescription work together to provide an accurate and personalized vision correction solution. These are: 


  • Sphere

  • Cylinder

  • Axis

  • Add

  • Prism

  • Pupillary distance


Familiarizing yourself with these terms helps you make informed discussions with your eye care professional. You can choose the right frames and lenses to achieve optimal visual acuity. Always consult your optician if you have doubts about your eyeglass prescription. 



Regular eye examinations are also essential to monitor changes in your vision and update your prescription as needed. As your vision evolves, your prescription may require adjustments. This is to ensure that you continue to experience clear and comfortable vision.


For more on understanding your eyeglass prescription, visit Drs. Stein and Goldschneider at our Blackwood, New Jersey office. Call (856) 408-1800 to schedule an appointment today.