Changes in central corneal thickness values after instillation of oxybuprocaine hydrochloride 0.4%

Purpose: To assess the variation in central corneal thickness (CCT) following the instillation of oxybuprocaine hydrochloride (0.4%), in normal subjects. Methods: This was a randomized, prospective study of CCT measurements (before and after the instillation of topical anaesthesia) obtained with the Topcon SP-3000P noncontact specular microscope, in 60 eyes of thirty subjects. The subjects' mean age was 20 ± 1 years (mean ± SD). In each subject, one eye was treated with one drop of oxybuprocaine hydrochloride (HCl) and the fellow eye with one drop of normal saline (control). The SP-3000P CCT readings were first obtained before instillation (baseline) and monitored every 30. s after instillation of each eye drop for a period of 10. min. Results: The mean baseline CCT for oxybuprocaine was 526 ± 23 μm. Ten minutes after, it was 526 ± 24 μm. In the control, the mean CCT was 526 ± 27 μm, 10. min after it was 526 ± 28 μm. The mean variation in CCT measurement was -0.7 ± 3.1 (5.5 to -6.8 μm, 95% CI) for oxybuprocaine and -0.6 ± 4.1 μm (7.5 and -8.6 μm, 95% CI) for the fellow eyes (P>. 0.05). There was no significant variation among the 20 CCT columns for either oxybuprocaine or the control group (P>. 0.05 for both). Conclusions: One drop of topical oxybuprocaine 0.4% did not cause a significant change in CCT at up to 10. min following instillation. However, higher differences were observed at 2.30. min and 4.30. min after instillation.