Measuring Pantoscopic Tilt with an Inclinometer app on a Smart Phone

October 13, 2015

As the lens technology advances in today’s market, more and more digital/free form lenses are requesting the Position of Wear Measurements to personalize and optimize the best Rx for the patient. I find there are still many opticians that are not embracing this new technology. The biggest reason I hear is they do not feel comfortable taking the measurements. The offices that have invested in the automated type measuring devices are doing well with it. I understand some offices are not able to make the investment yet and these are the offices I would like to help.

In an article in 20/20 Magazine’s Opticains Hand Book titled Measuring Tilt and Wrap – An Easy Way, Mark Mattison-Shupnick and I collaborated on a way to measure the tilt and wrap in an inexpensive way. Below is another way you can accomplish these measurements.

We will need the 3 measurements– vertex distance, wrap angle, and pantoscopic tilt. Before you take any of these measurements, the frame should be adjusted to the “as worn” position.

Vertex Distance– Stand to the side of the patient and measure from their cornea to the front of the lens. Take this measurement and subtract the lens thickness = Vertex distance.




You can use a Distometer to find vertex distance.




Wrap Angle– Use one of the many lay-over charts that lens companies provide to determine the Wrap Angle.

Below is an example of Expert’s.




Pantoscopic Tilt: This one requires your Smart Phone. On my iPhone, I have a compass app (I would guess other Smart Phones would have something similar) Find your compass app and calibrate the compass (tilt phone and roll red ball around the circle until the compass appears). Once compass appears, swipe the screen left. The inclinometer should appear (if you have your phone flat on the table, it will be a bubble level). Hold the phone straight up and you will see the angle you are holding the phone at, compared to level to the ground. If you can, remove one of the lenses from the frame. Have your patient stand up and look at a distant object in their normal posture. Stand to the side of them and place the long edge of the phone against the top and bottom eyewires and read the angle (if you cannot remove the lens, place the edge of the phone on the lens and read the angle once you have the phone equal distances from the top eyewire and bottom eyewire).

Please note: Turn your phone to airplane mode before you do this. The patient may not appreciate a phone ringing in their face.



Robert Hughbanks ABOC, HOAA- Manager of Training and Development