Factors affecting ocular pulse amplitude in eyes with open angle glaucoma and glaucoma-suspect eyes.

ABSTRACT

PURPOSE: To investigate the associations between ocular pulse amplitude (OPA) as measured by dynamic contour tonometry (DCT) and ocular and systemic factors in patients with open angle glaucoma (OAG) and in glaucoma suspects. METHODS: One hundred and seventy-three glaucoma-suspect patients were consecutively enrolled. All subjects underwent intraocular pressure (IOP) measurement by DCT and Goldmann applanation tonometry (GAT), OPA measurement by DCT, Humphrey visual field (HVF) examination and central corneal thickness measurements. Arterial pulse amplitude (APA) and ocular perfusion pressure (OPP) were defined as the difference between systolic and diastolic BP and the difference between mean arterial pressure and IOP, respectively. All subjects also completed a systemized questionnaire on systemic vascular morbidities. RESULTS: Seventy-four eyes were diagnosed with OAG, based on HVF results. The overall mean CCT was 538.2±37.6 µm. In all 173 eyes, OPA was associated with spherical equivalent (SE, p<0.001) and with IOP by GAT (p=0.013) by multivariate analysis. Multivariate analysis of the 77 subgroup eyes of patients for whom BP parameters were available also revealed that OPA was associated with SE (p=0.007) and with IOP by GAT (p<0.001). When the subjects were classified into the groups with low, intermediate and high cardiovascular risk based on the questionnaire, there was no difference in OPA among these groups (p>0.05). CONCLUSIONS: Ocular pulse amplitude was associated with IOP measured by GAT and SE in patients with OAG and in glaucoma suspects. There was neither significant correlation between systemic hemodynamic parameters and OPA, nor difference of OPA in patients with different cardiovascular risk. OPA is primarily a measure of pressure, and there are certain limitations towards its use as a hemodynamic index.