Contact Lenses: How to read your Contact Lens Prescription

*Sample Prescription*

So, you’ve got a new prescription for Contact Lenses and you’re not quite sure what it all means. Maybe you’d like to order Contacts 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 get you the Contact Lens product that the Eye Doctor has prescribed for you.

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

(Above is a sample Contact Lens prescription. Each section is lettered to help you identify what each section is used 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: The “B.C.” or “Base Curve” refers to the Contact Lens curvature that the doctor has found best suits the curve of your cornea. This, along with the “Diameter”, are one of the reasons why the Contact Lens exam is so important. It’s the best way to get the most accurate fit for your Contact Lenses. Each contact lens may have a different “B.C.” and you want to get the one that works best for you, specifically. The figures in this field will be in decimal form, generally between 7.x and 9.x (‘X’ is whatever readings the doctor supplies).

F: The “DIA” or “Diameter” refers to the size of the contact lens. When performing a Contact Lens exam, the doctor will determine which lens is the correct curvature as well as the correct size or “Diameter”. Since most common contact lenses are generally circular, the size is measured from one end of the circle to the other end. The purpose of selecting the correct diameter is to ensure maximum breathability for your eyes and the lenses and maximum comfort while wearing the lens. If the lens is too big or too small, you could experience visual discomfort as well as physical discomfort while wearing the lenses. The figures in this area are also in decimal form, generally between 13.x and 15.x (‘X’ is whatever readings the doctor supplies)

G: The “Mult. Power” or “Multifocal Power” would be used for patients who require a Multifocal contact lens. This selection is mostly used for presbyopic (people that need additional help seeing up close) patients. The doctor will generally signify a Hi-Add, Med-Add or Lo-Add for the patients that require these lenses. If neither one of those selections are specified, the doctor may opt to write out the actual ADD POWER. Your Licensed Optician can determine, based on the prescription, which ADD POWER to order for you.

H: This area can be a bit tricky at times as some doctors may give a few options for different Contact Lenses. But, this area is where the doctor will prescribe a specific BRAND of contact lens based on all the figures and findings explained above. Not every brand has ALL prescription strengths or cover every Base Curve & Diameter. Many brands are limited to a specific set of values. So, the doctor, along with your guidance, will prescribe the brand that is best you (Visually & Comfort-wise) and fits your eyes the best, based on the exam findings.

There are many different types of contact lenses and a wide array of applications for each. The sample and explanations above reference standard soft contact lenses that are commonly used in most optical practices. If a more specialized contact lens is required, many of the explanations above will still apply, but there may be a few additional items that the doctor must supply for the Optician to get the correct lens ordered for you. Consult your Eye Doctor and your Licensed Optician if you’d like to try contact lenses for the first time or get a renewal on your last contact lens prescription.