Contact Lens Prescriptions: What You Need to Know

Contact lenses are a great way to achieve the vision correction you need to enjoy clear eyesight. There are a lot of options available to you, but whatever contact lenses you choose, whether you opt for orthokeratology or more standard ones, you will need a prescription. And, to determine what you need exactly, it’s in your best interest to understand your contact lens prescription.

What Do All These Letters Mean?

• OD and OS – Referring to your right and left eyes, respectively, OD is Latin for “oculus dexter” while OS is Latin for “oculus sinister”. If you see OU, it means “oculus uterque” or each eye, which means the measurement provided applies to both of your eyes.

• PWR – Referring to refractive power, it is the level of correction your eyes need to give you 20/20 vision. It is measured in diopters and is accompanied by the minus or plus signs. A minus sign means you have myopia or are nearsighted while a plus sign means you have hyperopia or are farsighted. The larger the number, the stronger your prescription. This applies to standard and ortho-k lenses.

• DIA – Referring to diameter, it measures the distance across the surface of contact lenses. Measured in millimeters, it determines where on the eye a contact lens will sit. The correct DIA is critical to contact lens comfort and avoiding eye scratches.

• BC – Referring to the base curve, it determines the back curvature of contact lenses. Measured in millimeters, it should match with the corneal curvature for a perfect fit. If a prescription doesn’t come with a base curve, it is likely that your brand comes in only one base curve size.

Do Contact Lens Prescriptions Expire?

Contact lens prescriptions are valid for at least one year or whatever the minimum required is by laws in your state, whichever is greater. It is important to note that your vision correction needs may change, so it will pay to have an updated prescription before you get new contact lenses. Updating your prescription will involve an eye exam to determine your current eye health and how your last pair may have affected your eyes.

Need to get new contact lenses?

For eye doctors you can trust, look no further than Insight Vision Center Optometry. To learn more about what we can do for you, simply give us a call at (714) 486-3315, or fill out our contact form. Schedule an appointment with us today! We serve Costa Mesa, Newport Beach and the surrounding communities.