Evaluation of discomfort of Goldmann tonometry without anaesthetic

Abstract

Goldmann applanation tonometry (GAT) is considered the gold standard technique for tonometry. It is a procedure involving administration of topical anaesthetic (a drug which could have several side effects). This prevents a large number of vision care practitioners from using GAT, due to legal restrictions regarding the use of these ophthalmic drugs. The purpose of this study was to establish whether the discomfort experienced during non-anaesthetic Goldmann Applanation Tonometry (NAGAT) would be acceptable to subjects. The intensity of pain inflicted by GAT, NAGAT, Non-Contact Tonometry (NCT) and Schirmer test was assessed on thirty-one subjects enrolled in the study using the Numerical Rating Scale (NRS) to assess pain. The GAT was performed on one eye and the other three procedures were carried out in random order on the fellow eye. Initially, each subject was asked to score their Maximum Pain Without Complaint (MPWC). The MPWC and the Schirmer test were used as references to grade the pain levels. The scores for the five procedures were registered using the NRS (0-10) and compared using a non-parametric statistical analysis (Friedman test and a post-hoc analysis). In addition, IOP results for GAT and NAGAT were also compared using the t-test. The scores obtained on the NRS ranged from 0-4, 0-5, 0-8, 0-7 and 3-8 with a median of 1, 1, 2, 2, and 5, respectively for NCT, GAT, NAGAT, Schirmer and MPWC. A statistically significant difference (p = 0.01) was found between the MPWC and the four clinical tests but no difference was found between the clinical tests. There was no statistically significant difference (p = 0.71) between the IOP results for GAT and NAGAT, 14.0 ± 2.0 mmHg and 13.8 ± 2.0 mmHg (mean ± 1S.D.) respectively. The Goldmann Applanation Tonometry without anaesthetic (NAGAT) can be performed with an acceptable level of discomfort for the majority of subjects and should be performed identically to a traditional GAT, informing the subjects about the possibility of feeling a small discomfort.