For many people, their spectacle prescription is a mystery of numbers and letters that only their optometrist/eye doctor seems to understand. However, understanding your prescription is key to ensuring that you get the most accurate and comfortable glasses for your needs—whether you're updating your lenses, choosing a new pair of frames. In this blog post, we’ll break down the elements of a spectacle prescription, explain what they mean, and how they affect your vision.
I am a qualified Dispensing Optician and so I understand all your eyewear needs. I interpret your prescription, and if I feel that the lens/frame combination you have selected is not suitable, I will get in touch before proceeding with your order. So you can always rest assured you will get the right spectacles for you.
So let's get back to basics, and gain some level of understanding of what your prescription actually means.
1. The Basics of a Spectacle Prescription
Your spectacle prescription is essentially a guide to how your lenses need to be made in order to correct your vision. It usually includes several numbers and abbreviations that specify the lens strength, type, and adjustments needed for each eye.
Let’s take a look at the key elements you’ll find:
- OD (Oculus Dexter) & OS (Oculus Sinister): These are Latin terms for the right eye (OD) and left eye (OS), respectively. On most prescriptions the right eye features first, but this can sometimes differ.
- Sphere (SPH): This number indicates the lens power needed to correct short-sightedness (myopia) or long-sightedness (hyperopia). If the number is negative (-), it means you're shortsighted and need help seeing faraway objects. If it’s positive (+), you’re longsighted and need correction to see objects close up.
- Cylinder (CYL): This part of the prescription is for people with astigmatism, which occurs when the cornea or lens of the eye is irregularly shaped. Your optician may have told you your eyes are "rugby ball" shaped. It represents the degree of astigmatism that needs to be corrected.
- Axis: For those with astigmatism, the axis number specifies the orientation of the astigmatism. It’s measured in degrees and helps your lenses focus light correctly on your retina.
- Add (Addition): If you require multifocal or bifocal lenses, the "Add" value shows the additional lens power needed to correct presbyopia, a condition where close-up vision becomes difficult as we age.
2. What Do These Numbers Mean for Your Glasses?
Each part of your prescription plays a role in how your glasses are customised to improve your vision. Here’s how the numbers and terms translate into the real world:
- SPH (Sphere): If your SPH number is -2.00, this means your lenses need to be concave, or "minus" lenses, to help you see distant objects more clearly. On the other hand, if it’s +2.00, your lenses need to be convex, or "plus" lenses, to help you focus on things up close.
- CYL (Cylinder) & Axis: These values work together to correct astigmatism. If you see a CYL value of -1.00 with an Axis of 180, it means your right or left eye requires a slight adjustment at the 180-degree orientation to make things sharper. Without this correction, objects might appear blurry or distorted at certain angles.
- Add: If your prescription includes an "Add" value, it means you need bifocals, progressive lenses, or reading glasses to assist with close-up vision. A typical addition might be +1.50, which is added to the SPH value to give you that extra near vision correction.
3. Why Are Prescriptions Different for Each Eye?
It’s very common for each eye to have different prescription values, which is why prescriptions list each eye separately. One eye may be more shortsighted or longsighted than the other, or only one eye may have astigmatism. This difference is completely normal and part of the reason why customised lenses are so important.
4. Can You Use the Same Prescription for Contact Lenses?
While your glasses and contact lenses may correct the same vision issues, the prescriptions are not the same. You must only order glasses or contact lenses with the correct prescription as mixing them up would affect your vision.
5. Prescription Terms You Might See:
- Prism: This is used in some prescriptions to correct double vision or issues related to eye alignment. It helps align the images seen by your eyes so they fuse into a single clear image.
- PD (Pupillary Distance): Although not part of the prescription and is often not written on your prescription, this measurement is important for ensuring your lenses are centred correctly in relation to your pupils. When ordering new glasses, having your PD handy ensures your lenses are aligned correctly with your eyes. There are numerous app's that can help you measure this at home, such as GlassesOn.
6. How We Turn Your Prescription into the Perfect Pair of Glasses
Once you understand your prescription, you might wonder how it translates into actual eyewear. At our Retro Spectacle, we specialise in fitting your unique prescription into both vintage glasses and sunglasses frames. We can even fit lenses into your existing glasses. Here’s how the process works:
- Lens Crafting: Whether you have a complex prescription involving astigmatism, multifocal lenses, or even prism correction, we work with precision to craft lenses tailored to your vision needs.
- Frame Compatibility: We ensure that your chosen frames, can comfortably accommodate your prescription. Some vintage frames might require slight adjustments to fit modern lenses, but we take special care to preserve the integrity of the design while providing optimal vision correction.
- Coatings and Customisation: Whether it’s adding an anti-glare coating, blue light protection, or transitioning lenses that darken in sunlight, we can customise your lenses to suit your lifestyle.
Demystifying Your Prescription for Better Vision
Understanding your spectacle prescription might seem daunting at first, but with a little knowledge, those numbers and abbreviations become much clearer. Your prescription is a blueprint for better vision, and knowing what it means empowers you to make informed choices about your eyewear.
At Retro Spectacle, we specialise in combining vintage style with modern optical technology, ensuring you not only look great but see clearly, too. Whether you’re looking for custom lenses for a pair of classic frames or need advice on updating your prescription, we’re here to help.