PD – The secret sauce for your prescription

The Pupillary Distance (commonly known as PD or Distance PD) is the secret sauce in your glasses prescription. It is rarely, if ever, included in the copy of the prescription that you receive (or should receive!) after your eye examination yet it is absolutely critical. An incorrect PD can result in strained eyes, headaches and worse, particularly for those with stronger prescriptions.

So what is the PD?

It is the distance between the centre of the pupils of your eyes, something designated as a single number (e.g. on average 63-65mm for men and 60mm for women) and more commonly as a Dual PD – the distance between the centre of each eye and the middle of the bridge of your nose (e.g. PD(Left) = 31.5mm ; PD(Right) = 33mm). These distances might be different so the Dual PD is a more accurate measurement and is ideally the one you want (especially if you have a wonky nose like me!).

What is the PD for?

The PD allows the lens crafter to accurately position the optical centre of each lens with centre of each pupil. This means that the corrective power of the lens is in perfect alignment with your field of vision – exactly what you’re looking for.

An inaccurate PD can mean that the perfect focal point of your lens could be slightly off and the stronger the correction required, the more this effect is exacerbated, leading to discomfort.

For multifocal lenses (bifocal or progressive) where there is a “distance” requirement for e.g. driving and a “reading” requirement for close-up detail there are two PD’s – the Distance PD and the Near PD where the Near PD is typically 3-4mm less than the Distance PD and allows the lens crafter to compensate for the effect when your eyes “narrow” to focus on nearby items.

How do I get my PD?

So, if you want to order glasses online it is very important that you ask your Optician for your PD. As mentioned above, the PD typically isn’t written down on your prescription so you may have to ask your optician for it. Then, when you order online at Easy Optical you’ll be able to enter your PD as part of the order process or you can send it to with along with your other prescription details if you prefer.

About Easy Optical

If you need prescription glasses, sunglasses or even over-the-counter reading glasses, visit our website (www.easyoptical.com) and we’ll be happy to help.