What are the causes of non-tolerance to new spectacles and how can they be avoided?

Given that overplus-underminus was a much bigger proportion of prescription-related cases than overminus-underplus (26% vs. 11%), the refraction mantra of "maximum plus for maximum VA" should be balanced by increased teaching of the problems of overplusing and underminusing, and the use of prescribing guidelines. In addition, continuing professional development regarding the basics of the recheck examination, refraction, visual acuity and prism determination is needed. Changes of oblique cylinders should be carefully considered in older patients as this is a common cause of non-tolerance. In addition, if the "if it ain't broke, don't fix it" and related maxims had been applied to all patients who were asymptomatic at the original examination, one third of all non-tolerance cases could have been avoided. Finally, it would seem appropriate for practices to develop a system to deal better with non-tolerance cases. Perhaps an experienced clinician should examine all patients with non-tolerance and provide feedback to the original clinician.