Effects of Valsalva Maneuver on Anterior Chamber Parameters and Choroidal Thickness in Healthy Chinese: An AS-OCT and SS-OCT Study.

Abstract

This study concurrently evaluated the effects of the Valsalva maneuver (VM) on the anterior and posterior ocular biometric parameters in a healthy Chinese cohort. This prospective, cross-sectional study used anterior segment optical coherence tomography (AS-OCT) and swept-source optical coherence tomography (SS-OCT) to measure the anterior and posterior ocular biometric parameters before and during the VM. Sixty-three volunteers (126 eyes; 17 males and 46 females) were enrolled. The IOP, blood pressure (BP), and refractive error were recorded before and during a VM. The mean IOP showed a statistically significant increase (from 13.86-14.25 mm Hg, P = 0.005), but the different layers of the retina and the choroidal thickness (CT) showed no significant changes. The anterior chamber parameters decreased sharply from the baseline, with a smaller angle opening distance (AOD500; from 0.35-0.31 mm, P < 0.001), AOD750 (from 0.44-0.39 mm, P = 0.007), trabecular-iris space area (TISA500; from 0.14-0.13 mm, P = 0.027), TISA750 (from 0.25-0.23 mm, P = 0.007), and anterior chamber volume (ACV; from 143.09-139.84 mm3P = 0.036). Regression analyses revealed an association between ΔIOP and the baseline IOP (β = 0.26 [0.15, 0.37], P < 0.001) and ΔACW (β = -3.24 [-5.65, -0.83], P = 0.008). This study is the first to provide simultaneous evaluation of the effects of the VM on anterior and posterior ocular biometric parameters. The VM caused a significant IOP increase and narrowing of the angles in healthy subjects. However, it did not change the CT in the macular region. The relationship between IOP elevation and choroidal expansion during the VM needs further investigation.