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

Purpose: To investigate non-tolerance cases from several UK practices to determine their likely causes and how they might have been avoided.

Methods: Patient complaint and refraction data were collected from non-tolerance recheck examinations. For one practice, clinical data were also collected retrospectively to investigate the quality of the eye examinations.

Results: Data for 279 rechecks were gathered from 10 practices and a recheck frequency of 2.3% was found. The mean patient age was 60 (SD 16) years, with cylinder changes responsible for 38% of prescription-related causes of rechecks, overplusing or underminusing 26%, and underplusing or overminusing just 11%. An assessment of 242 recheck corrections found that 40% were unsatisfactory (e.g., failed to address initial or recheck symptoms, N = 45) and retrospective analysis of 217 case records showed many limitations (e.g., 61% or 28% recorded no uncorrected or habitual visual acuity (VA) at either initial examination or recheck).

Conclusions: 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.