How Strong Is My Eye Prescription?
Your prescription is made up of several different measurements. SPH (sphere) records your short- or long-sightedness. If it’s positive, you’re long-sighted, and vice versa. The closer you are to 0, the less severe your vision. Add or CYL (cylinder) are measurements only relevant to presbyopia and astigmatism respectively, and won’t feature on most prescriptions. Finally, there’s PD (pupillary distance). If you’re a glasses wearer, you’ll likely have a copy of your prescription so you can purchase new glasses.