Most of the displays are reflective enough to work as a mirror, such that it is possible for the user to see in it the reflection of his own face, specifically when the background of the display is dark and under certain light conditions. Aligning two circular marks on both pupils, customers are able to find their Pupillary Distance.
1. Place your Tablet (iPad, iPhone or Android) about 10 inches away from your face. In order to keep steady, please be seated at a desk and rest your elbows on the desk. Ensure your are in a well-lit place and that your face is well illuminated.
2. Look at the black areas of the App and notice the reflection of your eyes in the dark areas.
3. Now line your left eye reflection up so it is inside of the left circle. While you are lining up your left eye, you may close your right eye (optional).
4. Keeping your head and Tablet still, now line up your right eye moving the right circle using the buttons on the bottom of the app. While you are lining up your right eye, you may close your left eye (optional).
5. Ensure both eyes are aligned on both circles at the same time. Otherwise repeat the aligning process. Once lined up, the reading of the PD number is the Pupillary Distance.
The "mirror" is nonexistent. Could not see my eyes at all. Too bad.
Impossible to get an accurate measurement