Having the perfect edge, is important for lens comfort, proper oxygen delivery to the cornea and easy lens removal. An edge should be smooth and well blended.¹

The concept of edge lift describes the edge shape that is formed by a series of peripheral curves. Specified in an axial (AEL) and radial direction (REL). ^1,2 

Axial Edge Lift (AEL) is defined as the distance between a point on the back surface of a lens at a specific diameter and the extension of the back central optic zone, measured parallel to the lens.¹

1. Laäs C, Eksteen C, Booysen D. The art of contact lens fitting. 2005
2. Douthwaite, WA. Contact Lens Optics and Lens Design. Third Edition. Butterworth-Heinemann Ltd, 2006:57-80,100-102