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How to Transpose Your Glasses Prescription

During a refraction, your optometrist or ophthalmologist may use different equipment which can result in a lens prescription being written in either a plus (+) cylinder or a minus (-) cylinder notation. However, the optical properties of the lens remain consistent regardless of the prescription form. To make the process of transposing the prescription simpler, the optometric transposition calculator has been developed. By entering the correct lens formula, your prescription will be automatically converted into the corresponding lens parameters.

Transposition Calculator

Transposition Calculator


Transposed Sphere: 0.00

Transposed Cylinder: 0.00

Transposed Axis: 0.00

How to Transpose a Glasses Prescription

Glasses or contact lens prescriptions are crucial for ensuring clear vision and optimal eye health. When it comes to getting a new pair of glasses, it’s essential to understand how to transpose a glasses prescription accurately. Transposing a prescription involves converting the numerical values from one format to another, ensuring that the new glasses provide the correct vision correction. In this article, we will guide you through the process of transposing a glasses prescription, based on information from Optical Academy.

Understanding the Basics

Before diving into the process, it’s important to grasp the basics of a glasses prescription. A standard prescription typically includes five parameters:

1. Sphere: Often abbreviated as ‘SPH,’ this number indicates the level of nearsightedness or farsightedness. Negative values (-) represent nearsightedness, while positive values (+) indicate farsightedness.

2. Cylinder: Abbreviated as ‘CYL,’ this number indicates the level of astigmatism correction required. It can be positive or negative, and if present, is always accompanied by an axis value.

3. Axis: Usually expressed as a number from 1 to 180, this indicates the orientation of the astigmatism correction required.

4. Add: Commonly abbreviated as ‘ADD,’ this value is specific to multifocal prescriptions for individuals with presbyopia. It indicates the additional power required for near vision.

5. Prism: If present, a prism prescription addresses issues with eye alignment. It involves three components: the direction (base direction), the amount (prism diopters), and the location (base orientation).

Transposing the Prescription

To transpose a glasses prescription accurately, follow these steps:

1. Gather information: Collect the original prescription from your eye care professional, ensuring you have all the parameters mentioned above.

2. Identify the format: Determine the format of your prescription, as they can differ based on the country or the doctor’s preference. The most common formats are plus/minus cylinder or minus/plus cylinder.

3. Convert formats if necessary: If your original prescription is in a different format than what your eyeglass provider uses, you will need to convert it. This typically involves changing the sign of the cylinder and adjusting the axis accordingly. If you are unsure about this step, consult with your optician for guidance.

4. Make necessary adjustments: If your eyeglass prescription contains a prism, it’s important to transpose this information accurately as well. The base direction, prism diopters, and base orientation must be precisely transferred to the new prescription.

5. Check for errors: Once you have transposed the prescription, double-check the values to ensure accuracy. Mistakes in transposing can lead to improper vision correction and discomfort.

6. Consult with an optometrist: Finally, take your transposed prescription to an optical or optometry practice that can assist you with selecting the right frames and lenses to match your vision requirements.

Importance of Professional Assistance

While transposing a glasses prescription seems straightforward, it’s crucial to remember that this process requires precision and attention to detail. Consulting a qualified optician or eyeglass provider is highly recommended, as they possess the expertise to ensure an accurate prescription transcription. They can guide you through the process, answer any questions, and help you find the ideal glasses for your needs.

In conclusion, understanding how to transpose a glasses prescription is essential for obtaining accurate vision correction. By following the steps outlined above and seeking professional guidance when necessary, you can ensure a smooth and successful transition to your new pair of glasses. Remember, prioritizing your eye health is key, so don’t hesitate to consult with an eye care professional throughout the process.