When it comes to getting a new pair of glasses, understanding your prescription is crucial. The numbers and abbreviations on your prescription may seem confusing at first, but they hold valuable information about your eyesight. In this blog post, we will break down the different components of a glasses prescription and explain what each number means.
What is a glasses prescription?
A glasses prescription is a written document provided by an optometrist or ophthalmologist that specifies the corrective lenses needed to improve your vision. It contains several numbers and abbreviations that describe the refractive error of your eyes.
What do the numbers mean?
The numbers on your glasses prescription represent the lens power required to correct your vision. They are typically written in a standardized format, with separate values for each eye.
Sphere (SPH)
The sphere, or SPH, indicates the lens power needed to correct nearsightedness (myopia) or farsightedness (hyperopia). A negative value (-) indicates nearsightedness, while a positive value (+) indicates farsightedness. The higher the number, the stronger the prescription.
Cylinder (CYL)
The cylinder, or CYL, is used to correct astigmatism, which occurs when the cornea or lens of the eye is irregularly shaped. It measures the amount of lens power needed to correct the astigmatism. If you have no astigmatism, this value will be listed as "0.00" or "Plano."
Axis
The axis is a number between 0 and 180 degrees that indicates the orientation of the astigmatism correction. It is only present if you have a cylinder value greater than zero.
Add
The add, or ADD, is an additional power that is added to the distance prescription for individuals who require reading glasses or bifocals. It is usually indicated as a positive value and is used to correct presbyopia, an age-related condition that affects near vision.
Pupillary Distance (PD)
The pupillary distance, or PD, is the measurement between the centers of your pupils. It is an important measurement for ensuring that your lenses are properly aligned with your eyes. Your PD may be listed as a single number (e.g., 62mm) or as two separate values for each eye (e.g., 31/31mm).
Conclusion
Understanding the numbers in your glasses prescription is essential for selecting the right lenses to improve your vision. By knowing what each number represents, you can make informed decisions when choosing frames and lenses that suit your needs. Remember to consult with an eye care professional if you have any questions or concerns about your prescription.