What do all the acronyms on my prescription mean?
• OD “oculus dexter” indicates your right eye’s parameters
• OS “oculus sinister” shows your left eye’s parameters
• SPH “sphere” indicates the amount of lens power prescribed for nearsighted or farsighted vision. It's measured in diopter, using (+) for farsightedness (hyperopia) and (-) for nearsightedness (myopia)
• CYL & AXIS: Both Cylinder (CYL) and Axis numbers (between 0 and 180 degrees) are required to correct Astigmatism
• ADD provides magnifying power for reading, bifocal, multifocal, and progressive lenses. You'll most likely have the same number for both eyes, ranging between +0.75 and +3.00
Some glasses prescriptions also include additional numbers such as:
• PD (Pupillary Distance) is the distance between the centre of your pupils, measured in millimetres (mm). It indicates where the optical centre of your lenses should be placed so you can have the best, most comfortable vision
• Prism: measured in prismatic diopter and only required when eye alignment needs assistance. We're unable to offer prism prescription glasses, as we believe a prism prescription is best filled by the eye doctor.
For more information, read our blog article on how to read a prescription.
What do all the acronyms on my contacts prescription mean?
• Base Curve (BC) indicates your contact lens’ shape. Depending on the steepness or flatness of your cornea, it'll determine how large your contact lens should be
• Diameter (DIA) indicates your contacts’ length to ensure your cornea is covered properly
• Brand: your eye doctor determines the right brand and lens type based on your vision needs, preferences, and specific requirements
• Expiration date: your eye care doctor provides an expiry date for your prescription. Generally, your contacts prescription lasts a year—after that, you'll need to get a new prescription.
• Corrective power: Sphere, Cylinder, Axis, and ADD indicate the power needed in your contacts. These numbers often change (or disappear) between your glasses and your contacts prescription, especially with higher powers.
For more information, read our blog article on how to read a prescription.