Millions of people all around the world that use contact lenses, and it can be difficult to get used to wearing them. Contact lens users have to get used to inserting and removing their lenses, in addition to establishing a routine of cleaning them properly. It can take some time to adjust to contact lenses, whether you have been wearing glasses for years or are new to corrective lenses altogether.


Here, we examine how to read your contact lens prescription the right way. It goes without saying that not using your contact lenses the right way can cause an array of issues, and it’s also essential to understand what your contact lens prescription really means. Here is how to read contact lens prescriptions and get it right the first time.


contact lens prescription


Do I Need a Prescription?


First and foremost, you should recognize that you will need a prescription for your new contact lenses. There are some countries where this isn’t the case. However, for the most part, you will require a prescription for contact lenses of any kind. In many cases, you will even need a prescription for colored contact lenses, which may be used for aesthetic purposes only.


Before you purchase contact lenses, make sure that you discuss contact lenses with an eye doctor. This will require an eye test, which is what is used to determine your prescription. You will also need to have a lens fitting to ensure your new lenses are suited to your eyes.


Glasses vs Contacts Prescription

contact lens prescription

One of the most important things to consider about reading a contact lens prescription is that it is much different from a glasses prescription. This is particularly important for those who may already have a prescription for their glasses and believe that they can use that same prescription for contact lenses. This is not the case.


Prescriptions for glasses use completely different metrics from contact lens prescriptions. Glasses have measurements that are based on the concave or convex curve of the lens as it sits in the frame, while contact lens prescriptions will contain a base curve, diameter, or contact lens name/manufacturer.


This shouldn’t come as much of a surprise, as contacts sit directly on the eyes, and glasses are usually expected to be about 12 mm from the eyes. Even though both glasses prescriptions and contact lens prescriptions are designed to correct/improve vision, their prescriptions are not the same and can’t be compared by their prescription specs alone.


Reading Your Contact Lens Prescription


There are many different aspects to a contact lens prescription, and they are typically made up of the following:

Base Curve: The base curve is usually a number between 8 and 10, but there is a chance that you will not see a base curve number if your brand only comes in one base curve number. The base curve, or BC, is a measure of the actual curvature of the contact lens.


The higher the base curve number, the flatter the contact lens will be. Some corneas are “steeper” or “flatter” than others, and your BC number will depend on your cornea shape.


Diameter: This number simply refers to the diameter of the contact lens, which is the measurement from one edge to another edge of the contact lens. It is measured in millimeters, and the diameter usually falls somewhere around 13-15 mm.


Power/Sphere: This figure refers to those who are either nearsighted or farsighted and require contact lenses. If you are nearsighted, then your figure will begin with a plus sign. If you are farsighted, then your figure will begin with a negative sign.


This value is the power of the lens needed to correct vision, whether you are nearsighted or farsighted. The higher the number, the stronger the visual correction is needed. The power/sphere is also included in the glasses prescription.


Expiration Date: Your contact lens prescription will also have an expiration date, which will help give you an idea of when they should be worn. This is also included in the glasses prescription.


Brand/Manufacturer: This is pretty straightforward – your prescription will likely include the brand/manufacturer of contact lenses.


Color: There are some situations where individuals might order a specific “tint” for contact lenses. Here, the color of that tint is described.


Axis: The axis may be abbreviated as AX. The AX is particularly relevant for those who suffer from astigmatism, which means that they suffer from an irregular curvature of the eye. The axis of the contact lenses refers to the angle of the correction that is needed to see clearly.


CYL: This is also included for those who suffer from astigmatism. CYL refers to extra visual requirements needed for astigmatism. The cylinder will always be a negative number and measured in increments of .25.


ADD: This number is required for bifocal contact lenses, and it describes the degree of magnification to certain portions of the contact lens. It is measured in diopters.


Dominant: This is relevant to those who require multifocal lenses or bifocal lenses. The dominant eye is denoted with a “D”, while the nondominant eye is denoted with an “N.”




One of the most important things to remember about eye care is to consult with an eye doctor to get the right contact lenses prescription, and to remember they are not the same as glasses prescriptions. There are some situations where you will have to read more into the contact lens prescriptions if you have specific eye conditions such as astigmatism. If you are confused about your contact lenses prescription, make sure to ask your eye doctor for more information or clarification.


You should also make sure that your contact lens prescription is good for at least one year, which is usually the case. If you find that your contact lenses are becoming uncomfortable or not fitting properly, you should consult with an eye doctor as soon as possible. It’s also important to remember that you will not be able to purchase contact lenses once your prescription expires.


And now you can renew your prescription online (for US buyers only), it’s hassle free and for as low as $25, try now!


Additional Readings

  1. 3 Signs you are Wearing Wrong Prescription Contact Lenses
  2. Prescription Contact Lenses: Difference between an Eye Test and Eye Exam