When it comes to purchasing sunglasses, you might have come across the term PD. PD stands for Pupillary Distance, and it plays a crucial role in ensuring the perfect fit and visual comfort of your sunglasses. In this article, we will explore what PD is, why it is essential for sunglasses, how to measure it, and what information is needed for customizing prescription sunglasses.
What is PD?
Pupillary Distance (PD) refers to the distance between the centers of your pupils. It is measured in millimeters and plays a significant role in aligning the optical centers of the lenses with your eyes. Since everyone's face is unique, the PD measurement ensures that your sunglasses are personalized for your specific vision needs.
Why Do We Need PD for Sunglasses?
The proper alignment of the optical centers of the lenses with your pupils is essential for several reasons. First and foremost, it ensures optimal visual acuity. When the lenses are correctly aligned, the light entering your eyes will pass through the correct parts of the lenses, providing you with the sharpest and clearest vision possible.
Moreover, having the correct PD measurement helps to avoid issues such as eye strain, headaches, and distorted vision. If the lenses are not properly aligned with your pupils, you may experience discomfort and visual distortions, making it difficult to see clearly.
How to measure PD?
While it is best to have your PD measured by an optician or an eye care professional, you can also measure it yourself at home using a millimeter ruler and a mirror. Simply stand in front of the mirror, place the ruler against your brow bone, and measure the distance between the centers of your pupils. Repeat the measurement a few times to ensure accuracy.
It is worth noting that PD measurements for sunglasses are usually slightly different from those for regular eyeglasses. This is because sunglasses often have a different frame design and lens curvature, which can affect the optimal PD measurement.
What is needed for customizing prescription sunglasses?
If you require prescription sunglasses, there are a few additional measurements and details that are needed to customize them accurately. Your vision report should include the SPH (sphere), CYL (cylinder), and AXIS measurements, which indicate your refractive error and the astigmatism correction needed. These measurements ensure that the lenses are shaped precisely to provide you with the correct prescription power.
In the case of progressive lenses (multifocal lenses that correct both distance and near vision), an additional measurement called the ADD prescription is required. The ADD prescription indicates the additional power needed for near-vision correction in progressive lenses. Including this measurement in your prescription ensures that the progressive lenses are tailored to your specific vision needs.
Pupillary Distance (PD) is an essential measurement when it comes to selecting and customizing sunglasses. It ensures proper alignment of the lenses with your pupils, resulting in optimal visual acuity and comfort. Whether you are purchasing non-prescription sunglasses or prescription sunglasses, having an accurate PD measurement is crucial for a perfect fit and an enjoyable visual experience. Remember to consult with an optician or eye care professional to obtain the most accurate PD measurement for your sunglasses and enjoy the benefits of personalized eyewear.