Measure your pupillary distance (PD)
PD is the distance between your pupils, and it's used to help center a prescription correctly in your glasses. Please follow the steps below.
If you wear glasses, take them off for the selfie.
It also helps to be in a well-lit area with a clean background
Adjust you screen and look at the camera.
Keep your face centred.
Place any card with a magnetic strip under your nose or on your forehead and take a photo.
Make sure the card is touching your face with the stripe facing outward and right side up.