A Guide to Understanding Your Glasses Prescription:
If you’ve ever looked at your glasses prescription (Rx) and felt like you were deciphering a secret code, you’re not alone! Understanding what SPH, CYL, and Axis mean can help you make informed decisions about your eyewear. At Al-Aziz Optical, we believe that knowing your prescription empowers you to choose the right lenses for optimal vision.
In this guide, we’ll break down the different values on your eyeglasses prescription, explain their meanings, and help you understand how they affect your vision.
What is an Eyeglass Prescription (Rx)?
A glasses prescription is a detailed description of the lens power needed to correct your vision. It is issued by an optometrist or ophthalmologist after an eye exam. Unlike a contact lens prescription, which is customized for lenses that sit on the eye, an eyeglass prescription is designed for lenses that rest slightly away from the eye.
Each prescription includes numbers and abbreviations that indicate the correction required for nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. Understanding these terms is crucial when selecting the right glasses.
Breaking Down Your Glasses Prescription
Your eyeglasses prescription typically contains these elements:
OD & OS: Which Eye Needs Correction?
OD (Oculus Dexter): Right eye prescription
OS (Oculus Sinister): Left eye prescription
OU (Oculus Uterque): Both eyes (used when both eyes have the same prescription)
SPH (Sphere): Correcting Nearsightedness or Farsightedness
SPH (Sphere) value represents the lens power needed to correct vision.
A negative (-) SPH means you are nearsighted (myopia).
A positive (+) SPH means you are farsighted (hyperopia).
Example: SPH -2.00 D means you need correction for distance vision, while +1.50 D means you need correction for close-up tasks.
CYL (Cylinder) & Axis: Correcting Astigmatism
CYL (Cylinder) indicates the amount of correction required for astigmatism, an imperfection in the eye’s curvature that causes blurred vision.
Axis (measured in degrees from 0° to 180°) specifies the orientation of astigmatism correction.
Example: CYL -1.00 Axis 90° means the astigmatism correction is applied at a 90-degree meridian.
ADD (Addition): For Presbyopia & Reading Glasses
If you require bifocals, progressive lenses, or reading glasses, your prescription will include an ADD value.
Example: ADD +2.00 means an additional +2.00 D is needed for near vision
PD (Pupillary Distance): Ensuring Proper Lens Alignment
PD measures the distance (in mm) between your pupils to align the lenses correctly.
Incorrect PD can cause eye strain and discomfort.
Average PD Values:
Adults: 54mm – 74mm
Children: 43mm – 58mm
Prism: Correcting Eye Alignment Issues
Prism correction is needed for individuals with eye alignment problems, such as double vision or strabismus.
Measured in prism diopters (Δ), it helps redirect light so both eyes work together properly.
Example: PRISM 1.5Δ BD (Base Down) in OD means your right eye requires a slight downward shift for proper alignment.
Common Questions About Eyeglass Prescriptions
Q: What does SPH mean in my prescription?
SPH (Sphere) represents the strength of the lens needed to correct nearsightedness (negative values) or farsightedness (positive values).
Q: What does CYL mean on my prescription?
CYL (Cylinder) indicates the level of correction required for astigmatism, a condition where the cornea is irregularly shaped.
Q: What does Axis mean on my prescription?
Axis (0° – 180°) determines the orientation of the astigmatism correction in your lenses.
Q: What is PD, and why does it matter?
PD (Pupillary Distance) ensures that the lenses align correctly with your eyes, preventing eye strain and discomfort.
Final Thoughts: Understanding Your Prescription = Better Vision!
A clear understanding of your eyeglasses prescription ensures that you make the right choice when purchasing glasses. If you need professional advice, our team at Al-Aziz Optical is always ready to assist you.
Need help with your prescription? Visit Al-Aziz Optical today or reach to us through whatsapp or email!Â
