The ocular pulse amplitude at different intraocular pressure: a prospective study

Purpose: To investigate changes in ocular pulse amplitude (OPA) during a short-term increase in intraocular pressure (IOP) and to assess possible influences of biometrical properties of the eye, including central corneal thickness (CCT) and axial length. Methods: In a prospective, single centre study, OPA and IOP as measured by dynamic contour tonometry (DCT) were taken before baseline-and post-OPA (delta) intravitreal injection of 0.05 ml anti-vascular endothelial growth factor agents. Analysis was performed employing linear regression with baseline-and post (delta)-OPA differences as the dependent and post-IOP as well as delta IOP as the independent variable. A multilinear regression analysis with delta OPA as the dependent variable and baseline IOP, post-IOP, CCT and axial length as independent variables was conducted. Results: Forty eyes of 40 patients were included. IOP and OPA increased significantly after injection (IOP mean increase +/- SD: 17.83 +/- 9.83 mmHg, p < 0.001; OPA mean increase +/- SD: 1.39 +/- 1.16 mmHg, p < 0.001). For every mmHg increase in IOP, the OPA showed a linear increase of 0.05 mmHg (slope 0.05, 95% CI: 0.02-0.09, p = 0.003, r(2) = 0.20). Multiple regression analysis with delta OPA as the dependent variable revealed a partial correlation coefficient of 0.47 (p = 0.003) for post-IOP as the only significant contribution. Conclusion: A clear positive relationship between OPA measurements and IOP levels was shown in a clinical routine setting using DCT focusing on baseline and postinterventional comparisons of OPA values after intravitreal injections in patients with exudative age related macular degeneration. When considering the OPA for diagnostic purposes, we recommend indication of corresponding IOP values.