Continue writing the next sentence.

How to adjust eye glasses
Stand in front of a mirror and look straight ahead.
Position the eyeglasses so the middle of the lenses are located in the center of your eyes. This is the optical center and the ideal location for your eyeglasses.
All adjustments to your eyeglasses should be made to achieve this optimal position. If you have a bifocal lenses, the line should sit at the lower eyelid.