If you have been wearing glasses or contact lenses for a long time, then you have probably seen one of those contact lens prescriptions that include a lot of symbols, numbers, and abbreviations without really understanding what they refer to.
But nowadays, we find all those kinds of deals online for eyewear, and to be able to confidently shop, you will need to enter those details into the website. Therefore, understanding the meaning of those prescriptions is essential.
Keeping in mind that glasses prescription and contact lenses prescription are two totally different things. eyeglasses prescriptions do not include the information and measurements needed in a contact lens prescription.
Therefore, if you plan to get contact lenses, ask your doctor for a contact lens prescription, you can also ask them for another eyeglasses prescription in case you lost the contact lenses and needed the glasses until you receive the replacement.
Without further ado, let’s dive in and find out everything about those prescriptions...
What Does a Contact Lens Prescription Look Like?
The following table looks exactly like your contact lens prescription written by your doctor:
OD (Right eye)
OS (left eye)
Contact Lens Prescription
The contact lens prescription is the piece of paper your doctor hands you after a check-up, and it contains details about specifications such as diameter, base curve, and diameter. As well as other numbers for Axis and Cylinder for astigmatism patients.
In addition to Dominant and Addition numbers for patients who need presbyopia correction. The prescription for each eye might be different as well. You typically find this prescription on the blister packs that contain the lenses or on the end side of the eye contacts box.
Reading Contact Lens Prescription
Here are the abbreviations and symbols found in contact lens prescriptions and what each of them means:
- Eye: Which eye (right or left)
- PWR / SPH: PWR stands for power, SPH stands for the sphere. Both mean and refer to the same thing which is how strong your eyesight is. It will have either a plus or a minus next to it. A plus means that you are farsighted, while a minus means that you are shortsighted.
- BC: BC stands for base curve and it is always a number between 8 and 10. This number determines how flat your lens will be. The smaller the number the curvier the lens will be. Many brands choose to make only two base curve options in their lenses.
- DIA: DIA stands for diameter and it is the width of the lens measured in millimeters. The standard diameter is usually between 13.5 and 15 mm.
- Brand: The brand is also something that your doctor has to prescribe as each brand uses different water content and material. However, if you are looking to buy colored contacts, then any color within the same brand is fine.
- O.D (Right eye): OD is short for “oculus dexter”, and it translates to “ the right eye” in Latin. Which is always listed as the first thing in any prescription.
- O.S (Left eye): OS is short for “oculus sinister”, and it translates to “the left eye” in Latin. And it is always listed second in prescriptions.
Reading Toric Prescription (Astigmatism Correcting)
Toric means astigmatism correcting, some patients might need these types of prescriptions if they suffer from astigmatism. These types of prescriptions include two other abbreviations (CYL and AX).
- CYL: Cylinder (typically between -4.00 and +4.00)
- AX: Axis ( typically between 0 and 180)
Reading Presbyopia Prescriptions
This is referred to by the abbreviation “ADD” which is an additional number on the prescription which determines which level of correction the patient needs to have a clearer vision while at a close distance.
- ADD: which means extra strength or added power (usually between 0.50 and 3.00), this number is also referred to as high, medium, or low by some brands.
A small number of patients need lenses that are multifocal or bifocal, the correction in their case is determined by a non-dominant and a dominant eye. This is referred to by the letters “N” and “D” to establish which eye is which.
What You Need to Know about Contact Lens Prescription
- You cannot use the same prescription for both glasses and contact lenses. This is because your contact lens prescription contains so much more info about the measurements of the lens including the lens power.
- If you suffer from astigmatism, then the regular soft lenses will not correct it. However, your doctor can help correct it partially by manipulating the lens power.
- Your prescription expires typically after one year, afterward, you will need to get a new prescription.
- In some cases such as bifocal or toric eye, patients might need to have two different prescriptions; one for each eye. This means that they will need to have two different brands as well as different parameters for each eye.
Do I Have to Purchase a Specific Type of Brand?
Yes, as the brand is an important part of your prescription. Your doctor chooses the most convenient brand for your eyes. The incorrect brand can make you feel uncomfortable and irritated. This also differs from one patient to another.
Can I Use My Eyeglasses Prescription for Contact Lenses?
No, the eyeglasses prescription is different from the contact lenses prescription. The contact lenses prescription contains more information about the measurements of the lens as well as the lens power. Therefore, you will need to get a new prescription for contact lenses.
Learning to read your prescription could help you find out how your eyesight is changing and how to maintain and correct it. Also, it comes in handy when you shop for eyewear online by entering your prescription measurements.