Analysis of ocular pulse amplitude values in different pregnancy stages as measured by dynamic contour tonometry

Background: Orbital circulation is influenced by systemic hormonal status. Ocular pulse amplitude (OPA) is a surrogate measurement of choroidal blood flow. We investigated the OPA profile during different stages of pregnancy. Design: Cross-sectional study. Participants: We enrolled 24 pregnant and 25 non-pregnant women (age-matched controls). Methods: Data collected included age, pregnancy period, intraocular pressure (IOP), and central corneal thickness (CCT). Pascal dynamic contour tonometry was used to measure OPA values. The mean of three good quality measurements was used for the analysis. Whenever both eyes were eligible, the right eye was arbitrarily selected. Main Outcome Measures: Differences in OPA values between pregnant women (at each trimester) and non-pregnant controls. Results: Mean age and CCT were similar between pregnant women (27.8 ± 6 years, 547 ± 25 μm) and controls (28.9 ± 3.4 years, 546 ± 28 μm; P > 0.25). Pregnant women (mean gestation period, 20.4 ± 9 weeks) had a lower mean IOP than controls (11.4 ± 2.4 vs. 13 ± 2.1 mmHg; P = 0.02). Analysis of covariance (adjusting for IOP difference) revealed that OPA values in women in the 1st (3 ± 0.6 mmHg) and 2nd trimesters (2.5 ± 0.7 mmHg) of pregnancy were increased compared to those in the last trimester (1.8 ± 0.6 mmHg) and controls (2.1 ± 0.7; P < 0.05). Multivariate analysis showed that gestation period was the only variable associated with OPA values during pregnancy (r2 = 0.30, P < 0.01). Age, CCT, and IOP were not statistically significant in this model (P > 0.5). Conclusions: Our results suggest that OPA values are increased in the first two trimesters of pregnancy, returning to normal in the last 3 months. These changes in OPA values seem not be influenced by age, CCT, or IOP.