Glasses: How to read your Eyeglass (Spectacle) Prescription

*Sample Prescription*

So, you’ve got a new prescription for glasses and you’re not quite sure what it all means. Maybe you’d like to order glasses online or you just want to be informed on what your prescription is actually saying about your vision.

Eye Doctor’s prescriptions can look very different depending on the office you visit. Although the physical prescription may look a bit different, generally it will have all the items necessary to produce you a pair of glasses with your prescribed prescription.

Let’s dig into how to read your Spectacle Prescription and what everything on it means.

(Above is a sample eyeglass prescription. Each section is lettered to help you identify what each section is for)

Let’s dig in:

A: This is where the distinction between eyes are. “O.D.” relates to your Right Eye and “O.S.” relates to your Left Eye. The “O.D.” and “O.S.” are both acronyms, meaning “Oculus Dextrus” and “Oculus Sinister” in Latin.

B: This is where the “Sphere Power” of your prescription is placed. These figures generally go from “+/- 0.00 or PLANO” and usually increase by “+/- 0.25” increments.

C: This is the cylindrical portion of your prescription. Not everyone will have figures in this section. This is where your doctor will document the Astigmatism portion of your prescription, if you indeed have astigmatism.

D: This portion is your optical axis. The figures in this area go from 1-Degree up to 180-Degrees. The only time you will see any figures in this are is if you have a Cylindrical Power (Astigmatism). The axis, simply put, references the light passing through your eye at a certain angle. If there are no Cylinder Power values on your prescription for a certain eye, there should be no Axis values.

E: “ADD” or “ADD Power” is for patients that need a bit more assistance seeing up close. The “ADD Power” is exactly as it sounds; its additional strength ADDED to your prescription to help you see up close. This section will not have values for every patient, just those that require that additional help. The “ADD Power” will usually be in decimal form, ranging from +0.75 and usually up to as much as +4.00 and generally increases in 0.25 increments. If a patient does require an ADD Power above a +4.00 or below +0.75, your Licensed Optician can make the necessary arrangements to get any specialty lenses ordered for you.

F: The “Prism” on a prescription is for patients that require a specific type of vision correction. Usually, when Prism is prescribed, the doctor it trying to correct an ocular anomaly. Prism can be prescribed for many reason, but some common reasons are to correct double vision, to help visually balance the appearance of your eyes (for patients with ocular imbalances), for vision therapy and many other optical anomalies. A Prism tests will usually be performed by your doctor during your eye exam. Not everyone requires Prism in their prescription, so you likely wont see any figures in this field of your prescription. If you do require Prism, partner with your Eye Doctor and your Licensed Optician to ensure the correct prism is ordered for you as well as ensuring the aesthetic look of your eyewear will be appealing.

G: The “P.D.” or “Pupillary Distance” references the distance from the center of one pupil to the center of the other, in millimeters. When taken correctly, this measurement will aid in getting the Optical Center (the pin-point of your prescription) centered over your pupil so you can see the sharpest. Many times, the doctor will not have this measurement included in the prescription and you may have to get an optical professional to measure this for you. The “P.D.” isn’t generally something the doctor looks for during an Eye Exam, mainly because the distance between your eyes don’t really change what your prescription will be. The Pupillary Distance is generally taken by the Optician or Optical Staff during a transaction for glasses. The PD is a measurement necessary for the processing of prescription eyewear. If your doctor supplies the Pupillary Distance as a part of your prescription, keep it handy. If it is not supplied on your prescription, your Licensed Optician or Optical Expert can take this measurement for you as you place your order.

There are many ways to get a Pupillary Distance (Virtual, Digital, Predictive, etc.), but the most accurate will always be one taken by an Optical Professional.

H: In this section, this is where the doctor will usually make any additional recommendations for your prescription or vision needs. Sometimes, instead of “Notes”, this section may say “Recommendations” or something that will allow the doctor give additional information. This is where the doctor can communicate with the Optical Expert on what additional items are recommended for the patient’s vision care needs. Some items may be optional and others may be a vision necessity. Consult your Eye Doctor and your Licensed Optician to determine which items are a necessity and which are an option.