Investigation of the causes of non-tolerance to optometric prescriptions for spectacles

Objectives: To study non-tolerance to spectacle prescriptions in a busy community optometric practice, with several practitioners. Methods: A spectacle non-tolerance was defined in a pragmatic way, as a patient who had collected spectacles from the practice and subsequently returned because they were either having problems with, or were unable to wear, their new spectacles. Patients over 16 years of age, who met the above definition of non-tolerance were sequentially recruited over a 6 month period. Patients experiencing adaptation problems were first seen by a dispensing optician and any dispensing issues resolved. If the spectacle dispensing was felt to be correct, or if the non-tolerance persisted, then the patient was re-examined by an optometrist and the results analysed. Results: Non-tolerance examinations accounted for 62 of the 3091 eye examinations during the study period. The average rate of non-tolerance, averaged across the practitioners, was 1.8%, varying from 1.3-3.3% for individual practitioners. Gender was not a factor in non-tolerance, however age was, with presbyopes accounting for 88.1%. The most common reasons for non-tolerance were, in order of decreasing frequency: prescription related (61.0%), dispensing related (22.0%), pathology (8.5%), data entry error (6.8%) and binocular vision anomalies (1.7%). Of prescription related errors, gauging the spherical element accounted for the majority of inaccuracies, followed by problems with the near/intermediate addition. In every case, the final prescription was within 1.00 D of the not tolerated, prescription; 84.4% were within +/- 0.50 D. Conclusions: Spectacle prescription non-tolerance forms a small, but important, form of adverse reaction in optometric clinics. Most non-tolerances can be resolved by small changes, within 0.50 D, to the prescription.