Understanding the ADD Value in Your Prescription
The ADD value in your prescription plays a crucial role in near-vision correction, such as for reading or progressive lenses. This article explains what the ADD value is, when it is needed, and how it is applied to different types of glasses.
What is the ADD Value?
The ADD value represents the additional magnification required for near-vision tasks. It is typically used in reading glasses or progressive lenses to enhance clarity for close-up activities. For example, if you need glasses for reading or computer work, the ADD value helps adjust your prescription to meet these specific needs. However, for single-vision distance glasses, the ADD value is not required and should be omitted.
How is the ADD Value Used?
The ADD value is applied differently depending on the type of glasses:
Near/Reading Glasses: Add the full ADD value to the distance SPH (sphere) for each eye. This adjustment ensures optimal clarity for close-up tasks like reading.
Computer/Intermediate Glasses: Add half of the ADD value to the distance SPH for each eye. This adjustment is ideal for intermediate distances, such as working on a computer.
Other elements of your prescription, such as CYL (cylinder) and AXIS, typically remain unchanged unless specified by your eye care professional.
ADD Value and Viewing Distances
The strength of the ADD value determines the optimal viewing distance:
A higher ADD value (e.g., +1.75) is designed for closer viewing distances, such as reading a book.
A lower ADD value (e.g., +1.00) is better suited for intermediate distances, like computer work.
Simple Readers vs. Full Reading Prescriptions
There are two main types of reading glasses:
Simple Readers: These glasses use only the ADD value and provide the same magnification for both eyes. They are suitable for short, close-up tasks like reading books or menus. Simple readers are not customized for individual eye needs.
Full Reading Prescriptions: These are tailored to each eye and include all prescription parameters, such as SPH, CYL, and AXIS. Full reading prescriptions offer more precise vision correction and are ideal for extended or detailed tasks, such as computer work or prolonged reading.
FAQs
Do I need to include the ADD value for distance-only glasses?
No, the ADD value is only used for near-vision tasks, such as reading or progressive lenses. For distance-only glasses, the ADD value is not required and should be left out.
Can I set up my prescription for near vision only?
Yes, you can request a prescription specifically for near vision. Be sure to provide your prescription as a JPG or PDF so it can be applied correctly.
Does the regular prescription change when the ADD value is added?
No, the regular prescription remains the same. The ADD value is added to the distance SPH to create a near-vision prescription. For example, a prescription might look like this: OD: 0.00 -0.25 x122 ADD: +2.75 PD: 55.0; OS: -0.25 ADD: +2.75.