Centration

Every eyeglass lens contains a point through which we see the world most comfortably.

5. October 2022, Author: Paula Blahová, Photo: Jakub Čaprnka

At ZITA, we determine this point by precisely measuring the height of your pupil and the distance between both pupils from the bridge of your nose. In everyday language, we call this parameter your PD. We always take this measurement only after you've chosen your dream frame with us. Through proper centration, we prevent optical distortions and adapt the position of the lenses directly to you.

Pupillary distance and pupil height

With correct centration, the point we measure should align with the center of your pupil. Every millimeter matters here! Just a small deviation and your eye might be looking through the wrong point. Such misalignment causes eye strain or headaches, and you might simply never get used to your new glasses. The higher and more complex your prescription, the more crucial centration becomes.

Centration is one of the main reasons why it's essential for us to see you in person at the optician's. We get it – buying glasses online is convenient, but no digital technology on the internet can yet match a professional eye and equipment directly at the optician's. Centration through a webcam doesn't account for the natural head tilt we have when sitting at a computer. Even the smallest deviation can cause real trouble.

That's why we recommend leaving the alignment of your eyeglass lenses to us. At the shop, we always first make sure your frame sits nicely. It's important that it doesn't slide down your nose and has the proper angle to your face. Then we measure you using a special PD device. We make sure your head is in a natural position, and for accuracy, we center each eye separately. For multifocal lenses with addition, we also use our centration tower. We photograph you from several angles and obtain the most precise parameters for custom lens production. We then apply the centration data when grinding the eyeglass lenses to your frame.

The green dot marks the ideal centration point. The further the centration is from the ideal point, the more critical it becomes – marked by a gradual change from yellow to red.

Glasses are an important medical aid, and an individual approach to selecting them is therefore essential. Only in person can we be sure that everything fits as it should. Quick online shopping can harm your vision more than help it. That's why you won't find prescription eyeglass lenses on our online ZITA just yet. We're open to technology, but for now, a personal visit is still the greatest guarantee. Reserve your appointment for trying on glasses or a professional eye examination at our shop here.