Influence of topical anesthesia on tests diagnostic of blepharitis-associated dry eye syndrome

Despite the high frequency and clinical relevance of blepharitis-associated dry-eye syndrome, no agreement exists about whether diagnostic tests should be performed with or without topical anesthesia. The aim of this study was to compare the influence of topical anesthesia on the mean values of Schirmer's test, tear lysozyme, tear lactoferrin, and tear osmolarity in patients suffering from blepharitis-associated dry eye syndrome.

The authors compared the mean values of Schirmer's test, tear osmolarity, tear lysozyme (turbidimetric assay), and tear lactoferrin (radial immunodiffusion) before and after topical anesthesia in the following groups: 56 normal subjects (group 1), 62 blepharitis patients (group 2), and 15 patients with blepharitis-associated dry eye syndrome (group 3). All clinical and laboratory tests were performed by masked observers.

In group I, mean values of Schirmer's test decreased 24.8% (p < 0.01) when performed after application of topical anesthesia. The other tests were not significantly modified. In groups 2 and 3, significant differences were seen in Schirmer's test (25.33% and 24.19% respectively, p < 0.001) and the lysozyme determination (14.00% and 13.22% respectively, p < 0.01). Differences between the normal subjects (group I) and the patient groups increased when the tests were performed after application of topical anesthesia reaching statistical significance in group 3 for all the tests.

Performing diagnostic tests after topical anesthesia instillation could be useful in detecting dry eye associated with blepharitis.