How do you read your glasses prescription ?

Understanding your glasses prescription is essential for choosing the right correction for your vision. Whether you suffer from myopia, hyperopia, astigmatism, or presbyopia, knowing how to read and interpret the information provided by your ophthalmologist can help you better manage your visual health. Here's a guide to help you decipher common terms you might encounter on your prescription.

Key terms on your prescription

Right Eye (OD) / Left Eye (OS)

Your prescription will specify the corrections needed for each eye. OD stands for Right Eye, and OS stands for Left Eye. Example:

• OD: -2.00 (Sphere)
• OS: -1.50 (Sphere)

Sphere (SPH)

The spherical power of the lens measures the correction needed for myopia (blurred distance vision) or hyperopia (blurred near vision). A negative value indicates myopia (e.g., -2.00), and a positive value indicates hyperopia (e.g., +2.00).

Example:

• OD: -2.00
• OS: +1.00

Cylinder (CYL)

The cylindrical power of the lens corrects astigmatism, a condition where the curvature of the cornea is irregular, causing blurred or distorted vision. The cylinder can be positive or negative (e.g., -1.00).

Example:

• OD: -1.00
• OS: -0.50

Axis (AXIS)

The axis of rotation relative to the horizontal indicates the orientation of the correction for astigmatism, measured in degrees (e.g., 180°).

Example:

• OD: 180°
• OS: 90°

Add (Addition)

This term is mainly used for progressive lenses and single vision lenses for presbyopia. It indicates the additional power needed for near vision correction (e.g., +2.00).

Example:

• ADD: +2.00

Pupillary distance (PD)

Pupillary distance is the distance between the centers of your pupils. It is essential for the centering of the lenses in the frames.

Example:

• PD: 63 mm

Types of lenses

Single vision lenses

These lenses are designed to correct one distance of vision, whether for myopia, hyperopia, or astigmatism. These lenses are the most common and are generally used for people who need visual correction for one distance, either near or far.

Example: If you have myopia of -2.00, your single vision lens will be -2.00 diopters.

Progressive lenses

These lenses offer a gradual transition between different powers, allowing clear vision at all distances, ideal for presbyopes. Progressive lenses are particularly useful for people who need corrections at multiple distances, such as those with presbyopia.

Example:

If you have myopia of -2.00 and an addition of +2.00 for reading, progressive lenses will adjust the power for each vision distance.

Importance of eye exams

Regular eye exams are crucial for detecting changes in your vision and adjusting your prescription accordingly. It is important to note that a slight variation between exams is perfectly normal. These variations can depend on the time of day the exam is performed and your level of fatigue. For example, if you are tired or if the exam takes place at the end of the day, your vision may be slightly different than if the exam is conducted in the morning. Your prescription might include technical terms like diopters (the measure of the power of correction needed), indicating the spherical or cylindrical power required.

Why do variations occur?

Variations in eye exam results can be influenced by several factors, including:

• Fatigue: Your eyes may be more tired at the end of the day, which can affect the results.
• Time of Day: The clarity of your vision can fluctuate throughout the day.
• General Health: Conditions like dry eyes or allergies can temporarily affect your vision.
• Stress: Stress can also impact the accuracy of your vision during an exam.

Interpreting and selecting lenses

When choosing refurbished glasses, make sure to understand your prescription. Here are some tips:

• Check the spherical power of the lens for each eye (OD and OS).
• If you have astigmatism, note the cylindrical power of the lens and the axis.
• For presbyopes, ensure the addition for near vision is correct.
• Accurately measure the pupillary distance for optimal centering of the lenses.

Choosing the right refurbished glasses requires careful attention to these details to ensure that the visual correction is perfectly suited. Progressive lenses are often preferred for those who need multiple corrections, while single vision lenses are suitable for simple correction.

Example of a complete prescription

• OD (Right Eye): -2.00 SPH, -1.00 CYL, 180° AXIS
• OS (Left Eye): +1.00 SPH, -0.50 CYL, 90° AXIS
• Addition (ADD): +2.00 - Pupillary Distance (PD): 63 mm