Research shows that non-tolerance of a spectacle appliance, at approximately 2%, is a small part of optical practice. The consequences, however, can be far reaching in terms of wasted professional time and negative word of mouth. Preventing these issues arising will save both patient and practitioner time and stress.
This presentation will examine how important frame and lens choice is with regards to:
 

Lens thickness and spectacle comfort.
Optimisation for the base curve effect and compensations that are available within lens designs, including higher order aberration, frame parameters and eye rotation across the lens due to Listings Law.
Frame parameters (Back Vertex Distance (BVD), Pantoscopic Tilt (PT) and Wrap) and how they may cause aberration and lens performance and clarity.
How lens powers are compensated to correct for frame parameters.
How BVD and PT affect the corridor position in a progressive lens.
 

Finally, some new technologies with a view to calculating lens designs with respect to the individual eye rather than reduced eye models will be discussed.