Positional Change of Intraocular Pressure and Its Relationship to Ocular Pulse Amplitude

ABSTRACT

PURPOSE: To investigate the postural change of intraocular pressure (IOP) from sitting to supine position and determine the relationship to other ocular parameters including ocular pulse amplitude (OPA) in glaucoma suspect and open angle glaucoma patients. METHODS: The present study included 46 eyes of 46 patients. First, we measured IOP and OPA using Goldmann applanation tonometer (GAT), Pascal dynamic contour tonometer and TonoPen(R). Using TonoPen(R), the IOP was measured immediately after the subjects were placed in a supine position and 10 minutes and 30 minutes thereafter. We also investigated the correlation between positional change of IOP and axial length (AL), refractive error (RE), and OPA. RESULTS: IOPs of patients in a sitting position measured with GAT and TonoPen(R) were 15.3 +/- 3.3 mm Hg and 16.6 +/- 2.9 mm Hg, respectively, and OPA was 2.57 +/- 0.89 mm Hg. IOPs measured with TonoPen(R) were 17.6 +/- 2.9 mm Hg immediately after position change, 18.2 +/- 3.7 mm Hg after 10 minutes and 17.5 +/- 2.7 mm Hg after 30 minutes. Each IOP change was statistically significant and the largest change was after 10 minutes. Changes of IOP after 10 minutes were positively correlated with OPA (R = 0.340) and RE (R = 0.330) and negatively correlated with AL (R = -0.410). CONCLUSIONS: When placed in a supine position, the IOP of patients increased and then decreased over time. Positional IOP change was influenced by AL and OPA and variable hemodynamic factors and apparently influenced OPA and ocular perfusion pressure.