Have you recently had an eye exam? In this case, your ophthalmologist has probably given you a prescription for glasses.

The prescriptions are written in the same way all over the world, using numbers and abbreviations, for better universal understanding.

People generally have trouble reading their own prescriptions. Do you also face the same problem? Don’t worry! The experts at Lindegger Optical provide the perfect guide to understanding your prescription.

Explanation of abbreviations used

The first step in reading your prescription is to understand the meaning of the abbreviations on it. Traditionally, the abbreviations used were derived from Latin terms. But over time, some of these abbreviations have changed to make prescriptions easier to read.

Below is a list of the most commonly used abbreviations and their meaning:

OD, OS and OU

You will certainly find the abbreviated terms OD, OS and OU.

• OD are the abbreviations of Oculus Dexter for right eye;
• OS represents Oculus Sinister for left eye;
• OU refers to Oculus Uterque, which represents the two eyes.

These are the traditional abbreviations that ophthalmologists use when writing prescriptions. However, some ophthalmologists prefer to use French abbreviations such as OD, OG and ODG which represent successively the right eye, the left eye and both eyes (right and left eye).

VP or Work

VP or Work stands for Close Vision. VP is the prescription you need to correct your vision up close. This pair of glasses is perfect for jobs that require special attention.

VL or Distance

VL or Distance means Distance Vision. VL is the prescription you need to correct your distance vision. This pair of glasses is perfect for all activities, including hiking, driving, etc.

Intermediate Vision (VI)

VI stands for Intermediate Vision. This prescription is for people who need to correct their intermediate vision.

Sphere (SPH)

SPH is the lens power needed to correct your vision. A negative sign (-) means that you are nearsighted (you need correction for distance) and a positive sign (+) indicates that you are farsighted (you need correction for near).

The power of the lens is measured in diopters. For example ( -9.00 D) means that there are 9 diopters of myopia. The higher the number, the stronger the prescription.

Cylinder (CYL)

CYL or Cylinder indicates astigmatism, a condition in which the cornea is irregularly shaped, like a rugby ball causing blurred or distorted vision. The CYL number specifies the power of the lens needed to correct the astigmatism.

Like SPH, CYL is also measured in diopters and the value can be positive or negative, and in most cases the value will be between +/-0.25 and +/-4.00.

Axis

Axis indicates the direction of your astigmatism. It is defined by a number in degrees ranging from 1 to 180, where 90 represents the vertical position and 180 represents the horizontal position.

For example, Axis -180 degrees means that the astigmatism is horizontal.

This number only describes the direction of the astigmatism, it does not explain the strength of your prescription. The axis and cylinder will be required if you have astigmatism. The absence of these two numbers simply means that you do not have astigmatism.

Addition (Add)

Add means addition. This is the magnification power added to the bottom of multifocal lenses to correct presbyopia.

The number in this part of the prescription is always indicated with a plus sign (+) and appears only once, because the additional power is usually the same for both eyes. The value varies between +0.50 and +3.50. If you only need your glasses to correct nearsightedness or farsightedness and not for reading, this prescription is not necessary.

Prism

Measured in prismatic diopters (p.d.), prism is not commonly prescribed. It is only required when eye alignment requires assistance, usually in patients with strabismus or other eye muscle disorders.

Example of prescriptions for major eye defects

It’s not enough to learn all the important abbreviations, you also need to know how to read prescriptions for certain vision problems that glasses can compensate for.

In general, prescriptions follow an order from SPH refractive power, to CYL astigmatism, to AXE and finally to additional power [ADD]

{Beware – The two eyes may have different powers}

Myopia

Example of a prescription for a myopic person:

On the prescription: OD: -3.50 OG: -3.00

The (-) sign indicates nearsightedness, and the numbers indicate SPH – the lens power needed to correct distance vision.

Hyperopia

Example of a prescription for a hyperopic person:

On the prescription: OD: +3.00 OG: +3.70

The (+) sign indicates hyperopia, and the numbers indicate SPH – the lens power needed to correct near vision.

Astigmatism

Astigmatism can be added to the vision disorders already mentioned – such as myopia and hyperopia

Examples of prescriptions for a hyperopic and astigmatic person:

On the prescription: OD: +2.30 (+1.20) 90° OG: +3.70 (+0.65) 75° /

OD : (90°+1.20) +2.30 OG : (75°+0.65) +3.70

In this example of the right eye, +2.30 means hyperopic and SPH needed to correct near vision. While the numbers in parentheses indicate the astigmatism, i.e. CYL +1.20 (the lens power to correct the astigmatism) and 90° Axis (the direction of the astigmatism)

Presbyopia

Example of a prescription for a presbyopic and hyperopic person:

On the prescription: OD: +3.70 Add: 1.00 OG: +2.50 Add: 2.00

In this example of the left eye, +2.50 means hyperopic and SPH needed to correct near vision. Add: 2.00 indicates the magnification power added to the bottom of the multifocal lenses to correct presbyopia and to facilitate reading.

Example of a prescription for a myopic, presbyopic and astigmatic person:

On the prescription: OD: -2.50 (+0.65) 15° Add: 1.65 OG: -2.50 (+0.60) 90° Add: 2.65

In this example, the right eye, -2.50 means myopic and SPH needed to correct distance vision. While the numbers in parentheses indicate the astigmatism, i.e. CYL +0.65 (the lens power to correct the astigmatism) and Axis 15° (the direction of astigmatism). Add: 1.65 indicates the magnification power added to the bottom of multifocal lenses to correct presbyopia and to facilitate reading.

An eyeglass prescription is not the same as a contact lens prescription

Keep in mind that the prescription for your glasses is different from the prescription for your contact lenses, because of the difference in lens power. Another reason is that glasses are placed at a certain distance from the eyes, while contact lenses are placed directly on the eyes.

Do you have any questions? Contact our team at Lindegger Optique Rive in Geneva.

Book your eye test today at Lindegger Optique in Geneva.