Understanding Your Eye Prescription

June 14, 2022

Scheduling routine eye exams is the best way to keep your vision clear and your eyes healthy. During the exam, your eyes will be examined, and you may receive a prescription for corrective lenses. The prescription is essential to get eyeglasses or contact lenses that suit your eyes best.

Prescriptions can be hard to understand with the different abbreviations and numbers that make them. The following tips will help you comprehend your eye prescription.

Understanding Eye Prescriptions


Eyeglass and contact lens prescriptions contain several abbreviations and numbers. The numbers on the prescription relate to the visual strength and shape of the eyes. They help determine whether you are nearsighted, farsighted, or astigmatic and the degree of the refractive error.

It is vital to get the right prescription for correcting your vision. The right prescription will help prevent eyestrain, headaches, and a stinging or burning in the eyes.

The Common Abbreviations



  • OD (Ocular Dexter) and OS (Ocular Sinister): right eye and left eye

  • SPH (Sphere): Amount of lens power (in diopters) needed to correct the error

  • CYL (Cylinder): Amount of lens power for astigmatism in the eye

  • Axis: Lens meridian to correct astigmatism, a number between one and 180

  • Add: Additional magnifying power used for multifocal lenses that correct presbyopia

  • Prism: Prismatic power amount, prescribed to indicate eye alignment problems

Other abbreviations are BO (base out), BI (base in), BU (base up), BD (base down), DV (distance vision), NV (near vision), and PD (pupillary distance).

The Numbers on the Prescription


The abbreviations on the prescription are often followed by numbers marked by a plus (+), minus (-), or no sign. The plus or no sign indicates farsightedness, while the minus sign indicates nearsightedness.

Some numbers indicate the amount of vision correction required. The lens strength is measured in diopters. If the prescription has a high number, it indicates that the patient requires more vision correction.

Eyeglass Prescriptions vs. Contact Lens Prescriptions


There is a difference between prescriptions, and you cannot use your eyeglass prescription for contact lenses. You wear eyeglasses at a distance from your eyes, while contacts rest directly on the eye.

The eyeglass prescription lacks the information necessary to have clear vision with contact lenses. For contact lenses, you should schedule a contact lens fitting to help obtain the additional information. A contact lens prescription includes the base curve of the contact lens surface, the lens diameter, and the brand or manufacturer.

Getting Your Eye Prescription


The Federal Trade Commission requires that patients receive a copy of their eye prescription. After the eye exam, the eye doctor must give the patient a copy of the prescription. It gives the patient the freedom to purchase eyeglasses at a location of their choice.

The prescription is available if the patient asks for it, and it does not require an extra fee. The release is not conditional on the patient buying eyeglasses from a particular vendor.

Getting an eye prescription is not a one-time event. Your vision may change over time, so it is vital to get regular eye checkups. You need to get eye exams annually or every two years to get an updated prescription.

For more on eye prescription, visit Eye Associates of New York at our office in New York, New York. You can call (212) 650-4888 today to schedule an appointment.

Helpful Articles
admin none 9:00 AM - 5:00 PM 9:00 AM - 6:00 PM 8:00 AM - 7:00 PM 8:00 AM - 6:00 PM 9:00 AM - 4:00 PM Closed Closed optometrist # # #