Reading a contact lens prescription can sometimes feel like deciphering a code, especially if you’re new to wearing contact lenses. However, understanding the information written on the prescription is an important step in your contact lenses journey, to make sure you get the right lenses for your eyes. Below is a breakdown of the various elements typically found in a contact lens prescription:
Remember: glasses and contact lens prescriptions are different.
- OD and OS
OD (Oculus Dexter): Pertains to your right eye.
OS (Oculus Sinister): Pertains to your left eye.
Some prescriptions may use OU, which stands for “Oculus Uterque,” meaning both eyes.
- Base Curve (BC)
Expressed in millimetres, this measurement represents the curvature of the back surface of the contact lens. It is crucial for ensuring the lens fits well on the eye.
- Diameter (DIA)
This indicates the size of the contact lens in millimetres. It’s essential for a proper fit.
- Power/Sphere (PWR/SPH)
This number indicates the lens power required to correct your vision. A negative value corrects for near-sightedness (myopia), while a positive value is for farsightedness (hyperopia). i
- Cylinder (CYL) and Axis
These values are necessary for individuals with Astigmatism/Toric Lenses. The cylinder specifies the degree of the astigmatism, while the axis indicates its orientation. If your prescription doens’t have theses values then your lens type may be a Spherical or Multifocal Lens
Cylinder: This is always a negative number, representing the lens power required for astigmatism.
Axis: This is a number between 0 and 180 degrees, specifying the orientation of the astigmatism correction.
- Add Power (ADD)
This value is used for multifocal lenses and represents the magnifying power added to the bottom part of the lenses to correct presbyopia.
Your prescription may also specify a brand or type of lens suitable for you.
- Expiration Date
Contact lens prescriptions usually come with an expiration date, which is typically one year from the date of the eye exam. It is important to Stick to the Expiration date for your prescription to ensure the best possible visual and health results for your eyes.
(Example of Prescription)
Understanding these parameters will not only allow you to get the most suitable contact lenses but will also help you make better-informed decisions about your eye care.
Always consult with an optometrist to get a prescription that fits your specific needs.