How to Read My Glasses Prescription

Making sense of your eye prescription can feel like reading a different language – and that’s because it is. Eye prescriptions are written in Latin abbreviations. Learn what each abbreviation means and how to read your eyeglasses prescription.

How to Read Glasses Prescriptions

These are the common abbreviations you’ll find on your eyeglass prescription and what they mean:

• OS (Oculus Sinister): Refers to your right eye
• OD (Oculus Dextrus): Refers to your left eye
• OU (Oculus Uterque): Refers to both your eyes
• D (Diopter): This is represented by a number on your prescription that shows how much focusing power is needed to correct your vision
• PD (Pupillary Distance): This number is the distance between your pupils
• - (Minus Sign): A negative sign in front of the diopter number means you’re nearsighted
• + (Plus Sign): A plus sign in front of the diopter number means you’re farsighted

Other terms you’ll need to know to understand how to read glasses prescription are:

• Cylinder: This refers to the amount of astigmatism found in the eyes.
• Axis: This describes the position of the astigmatism in the eyes. Axis numbers are represented by degrees ranging from 1 to 180 on your prescription.
• Prism: This is a rare term used to prescribe prismatic power for those with eye alignment problems.
• Add: This describes the additional magnifying power required to correct presbyopia (a common condition of aging eyes) and is usually prescribed to those needing multifocal lenses. The number is typically the same for both eyes and is always a positive number.

What Do the Numbers on Glasses Prescription Mean

In general, the further away from zero the number on your prescription is, the worse your eyesight is and the stronger the focus power will be.

Need to update your prescription? We recommend having a yearly eye exam in order to catch any changes in your eyesight and to keep your prescription current. Schedule an appointment at your neighborhood Pearle Vision EyeCare Center to keep your prescription up to date.