Credit: ABDO
How to Read Your Glasses Prescription: A Complete Guide from a Qualified Dispensing Optician
For many people, their glasses prescription feels like a confusing mix of numbers, symbols and abbreviations that only and optometrist or eye doctor can decipher. But understanding your spectacle prescription is incredibly important - it helps you choose the right frames, select the best lenses and ensure your vision is corrected accurately and comfortably.
In this guide, I'll break down each part of your glasses prescription, explain what the numbers mean and show you how they translate into real-world eyewear.
As a qualified Dispensing Optician, I interpret prescriptions ever day. If I ever feel that your chosen frame or lens type isn't suitable for your prescription, I'll always get in touch before completing your order. You can rest assured that your eyewear will be crafted correctly and safely.
Credit: ABDO
- What is a Spectacle Prescrition?
Your spectacle prescription is essentially a blueprint that tells us how to make your lenses so they correct your vision properly. It contains several key measurements, each one describing a different aspect of your eyesight.
Credit: Retro Spectacle
Let's take a closer look at the main elements you'll see on your prescription
OD & OS
- OD (Oculus Dexter) - Right eye
- OS (Oculus Sinister) - Left eye
These traditional latin abbreviations are still widely used. Most prescriptions list the right eye first.
Sphere (SPH)
This number indicates the level of:
- Short-sightedness (myopia) if the number is negative (-)
- Long-sightedness (hyperopia) if the number is positive (+)
Cylinder (CYL)
This shows the amount of astigmatism, a condition caused by an irregularly shaped cornea or lens (often described as "rugby-ball shaped"). Not everyone has a Cyl value, only those with astigmatism.
Axis
The axis accompanies the CYL value and indicates the orientations of your astigmatism, measured in degrees from 0 to 180. It tells the lens where to place the corrective power.
Add (Addition)
This value appears on prescriptions for:
- Reading Glasses
- Bifocals
- Varifocals/progressives
It provides the extra focusing power needed for presbyopia, the natural age-related decline in near vision.
2. What Do These Numbers Mean for Your Glasses?
Every value on your prescription directly affects how your lenses are made.
Sphere (SPH) Example
- -2.00 SPH → a concave (minus) lens to help you see distance clearly
- +2.00 SPH → a convex (plus) lens for improved near vision
Cylinder (CYL) + Axis Example
If your prescription reads CYL -1.00 Axis 180, this means:
- Your eye has astigmatism
- The correcting power must be placed at the 180 meridian
Without this correction, objects can appear stretched, skewed or blurred.
Add Example
An Add +1.50 means 1.50 unites of extra magnifying power are added for comfortable near work such as reading, sewing or screen use .
3. Why Are Prescriptions Different for Each Eye?
It’s extremely common for each eye to have different prescription. One eye may be more short-sighted, long-sighted or astigmatic than the other. This is perfectly normal and one of the reasons custom-made lenses are so important.
4. Do Contact Lenses Use the Same Prescription as Glasses?
In short: no.
Contact lens prescriptions include different measurements and differ to the prescription used in your glasses.
5. Other Prescription Terms You Might See:
Prism
Used to correct:
- Double vision
- Eye alignment issues
Prism helps both eyes work together so images fuse comfortably into one.
PD (Pupillary Distance)
PD is not always included on your written prescrpition, but it's essential for making glasses. It ensures that the optical centres of your lenses align perfectly with your pupils.
If you don't know your PD, various apps are available so you can measure it at home.
6. How We Turn Your Prescription into the Perfect Pair of Glasses
At Retro Spectacle, we specialise in fitting vintage glasses and sunglasses with precision crafted lenses. We can even fit lenses into your current or beloved vintage frames.
✔ Precision 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 Checks
Some vintage frames require special handling or small adjustments. We always ensure your chosen frame can safely and comfortably accommodate your prescription.
✔Custom Lens Options
We offer a full range of enhancements including:
- Anti-reflection coatings
- Blue-light filters
- UV protection
- Transition/photochromic lenses
Your glasses can be tailored exactly to your lifestyle.
Demystifying Your Glasses Prescription
Understanding your spectacle prescription doesn't need to feel overwhelming. With a little guidance, those numbers and abbreviations become a meaningful map to clearer, more comfortable vision.
At Retro Spectacle, we combine authentic vintage style with modern optical expertise- so you don't just look great, you see great too.
If you ever need help interpreting your prescription or choosing the right lenses, I'm always here to assist.