Are you feeling a bit puzzled about understanding your eyeglass prescription? Don’t worry, whether you’re a newcomer to wearing glasses or a seasoned eyeglass wearer, deciphering your prescription can sometimes be a daunting task. But fret not! In this all-inclusive guide, I’ll break down the key elements of an eyeglass prescription and make it a breeze for you to comprehend. To make things clearer, I’ll throw in some examples and diagrams to help you navigate the world of eyeglass prescriptions with ease. So, let’s dive right into reading eyeglass prescription!
The Basics of an Eyeglass Prescription
Eyeglass prescriptions are written by eye care professionals to provide the necessary lens power to correct your vision. These prescriptions contain several terms and abbreviations to specify the type and amount of correction needed. Reading eyeglass prescription is important to ensure that you get the right lenses for your visual needs. Sometimes the abbreviations on the prescription are hard to understand, here’s a quick run-down of a few important abbreviations.
OD, OS, and OU: Right Eye, Left Eye, and Both Eyes
- OD (Oculus Dexter): Refers to your right eye.
- OS (Oculus Sinister): Refers to your left eye.
- OU (Oculus Uterque): Refers to both eyes.
Sphere (SPH): Understanding Your Prescription Strength
The sphere (SPH) value indicates the lens power needed to correct your vision. This value is measured in diopters (D).
- Positive (+) Sphere: Corrects hyperopia (farsightedness), meaning you have difficulty seeing objects up close.
- Negative (-) Sphere: Corrects myopia (nearsightedness), meaning you have difficulty seeing objects far away.
Example:
OD: -2.00 OS: -1.50
In this example, the right eye has a prescription of -2.00 diopters (nearsighted), and the left eye has a prescription of -1.50 diopters (also nearsighted).
For those with hyperopia or farsightedness, a positive sphere value helps correct difficulty in seeing objects up close. On the other hand, if you have myopia or nearsightedness, a negative sphere value will address the difficulty in seeing objects far away. The sphere value is essential when reading eyeglass prescription, it ensures that your eyeglasses provide you with the precise vision correction you need.
Cylinder (CYL) and Axis: Correcting Astigmatism
The cylinder and Axis also play a crucial role when reading eyeglass prescription, as they play a significant part in correcting astigmatism. If you have astigmatism, your prescription will include cylinder and axis values. Astigmatism occurs when the cornea or lens of the eye is irregularly shaped.
- Cylinder (CYL): Indicates the power needed to correct astigmatism, measured in diopters (D). Like sphere values, CYL can be positive or negative.
- Axis: Specifies the angle (in degrees) where the cylinder power is applied to correct astigmatism.
Example:
OD: -2.00 -1.25 x 180 OS: -1.50 -0.75 x 170
In this example, the right eye has a cylinder value of -1.25 and an axis of 180 degrees, and the left eye has a cylinder value of -0.75 and an axis of 170 degrees. This means both eyes have astigmatism that needs correction.
Addition (ADD): Presbyopia Correction
If you have presbyopia (age-related difficulty focusing on near objects), your prescription will include an addition (ADD) value. ADD is the extra magnifying power needed for reading or near-vision tasks and is typically applied to bifocal or progressive lenses. Here’s an example of ADD in reading eyeglass prescription.
Example:
OD: -2.00 -1.25 x 180 +2.00 OS: -1.50 -0.75 x 170 +2.00
In this example, both eyes have an addition value of +2.00, which means the wearer requires an additional +2.00 diopters of magnifying power for close-up tasks.
Prism and Base: Correcting Eye Alignment
Prism values are used to correct eye alignment issues, such as strabismus (crossed or misaligned eyes). Prisms are measured in prism diopters (Δ).
- Prism: Indicates the amount of prism needed to align the eyes correctly.
- Base: Specifies the direction of the prism base, which can be up, down, in, or out.
Example:
OD: -2.00 -1.25 x 180 +2.00 [2Δ BU] OS: -1.50 -0.75 x 170 +2.00 [1Δ BI]
In this example, the right eye has a 2Δ prism with the base up (BU), and the left eye has a 1Δ prism with the base in (BI).
Pupillary Distance (PD): Ensuring a Perfect Fit
Pupillary distance (PD) is the distance between the centers of your pupils, measured in millimeters (mm). This measurement ensures that your lenses are properly centered and aligned with your eyes.
Example:
PD: 62 mm
In this example, the pupillary distance is 62 mm.
Conclusion
Reading eyeglass prescription is essential for you to get the best vision correction possible. By familiarizing yourself with these terms and values, you’ll be better prepared to discuss your prescription with your eye care professional and make informed decisions about your eyewear.
