Your Eye Prescription: Understanding the Basics

Your eye prescription, often presented as a mix of numbers and abbreviations, holds the key to understanding your visual needs. Whether you’re a newcomer to corrective lenses or a seasoned wearer, interpreting your prescription doesn’t have to feel like unravelling a mystery. Here’s a straightforward guide on how to read an eye prescription:

1. Right Eye (OD) and Left Eye (OS)

Your prescription starts by distinguishing between your right and left eyes. “OD” stands for “oculus dexter” (right eye), while “OS” stands for “oculus sinister” (left eye). Each eye’s prescription is listed separately.

2. Sphere (SPH): Addressing short-sightedness or long-sightedness

The “sphere” value, represented by “SPH,” indicates whether you are short-sighted (myopic) or long-sighted (hyperopic). A positive value (+) indicates hyperopia, while a negative value (-) indicates myopia.

3. Cylinder (CYL) and (AXIS): Correcting Astigmatism

If you have astigmatism, your prescription includes values for “cylinder” (CYL) and “axis.” The cylinder value corrects the irregular curvature of the eye, while the axis specifies the orientation of this correction.

4. Addition (ADD): Adjusting for Presbyopia

For individuals with presbyopia, an age-related condition affecting near vision, the “addition” value (ADD) indicates the additional magnifying power required for reading or close work.

5. (PRISM) and (BASE): Correcting Eye Alignment

Prism correction may be prescribed for eye alignment issues, such as double vision. The prism value, measured in prism dioptres (Δ), and its base direction (up, down, in, or out) help align the eyes properly.

6. Pupillary Distance (PD): Ensuring Proper Fit

While not always included, the pupillary distance (PD) measures the distance between the centres of your pupils. This measurement is essential for ensuring that your glasses lenses align correctly with your eyes.

Understanding your eye prescription empowers you to make informed decisions about your vision correction options, whether it involves selecting glasses, contact lenses, or discussing surgical interventions with your eye care professional. Regular eye examinations are essential for monitoring changes in your prescription and maintaining optimal eye health. If you have any questions or concerns about your prescription, don’t hesitate to consult your optometrist or ophthalmologist for guidance.