What is the eye’s centre of rotation?

The eye’s centre of rotation Z’ is a central reference point in the optical design of single vision and multifocal spectacle lenses. It describes an imaginary fixed point around which the eye approximately shifts when looking in different directions. According to the Gullstrand schematic eye, it is located approximately 13.5 mm behind the anterior corneal vertex. The position of Z’ varies with axial length and the refractive distribution of the eye’s media and may differ from the average by several millimetres. Particularly with higher lens powers, taking the eye’s centre of rotation into account helps ensure clearer, more stable and more natural peripheral vision.