Valsalva Maneuver-induced Changes in Anterior Lamina Cribrosa Surface DEPTH: A Comparison Between Normal and Glaucomatous Eyes
The purpose of this study is to investigate the influence of the Valsalva maneuver (VM) on anterior lamina cribrosa surface depth (ALCSD), and to compare normal with treated glaucomatous eyes in terms of this effect.Methods:
Thirty-two patients (32 eyes) with early-to-moderate glaucoma under treatment and 30 normal healthy participants (30 eyes) were prospectively enrolled. Study subjects performed the VM by blowing through a mouthpiece attached to a handheld manometer; expiratory pressure during the maneuver ranged from 35 to 40 mm Hg. Swept-source optical coherence tomography B-scans were performed during phase 2 of the VM (from 10 to 15 s).Results:
The ALCSD was significantly different in the normal eyes only, decreasing by 31.90±14.81 μm (−8.79%; 394.85±53.63 μm at baseline vs. 362.95±44.23 μm during the VM; P<0.001). In the glaucomatous eyes, the ALCSD decreased by only 3.57±4.91 μm (−0.75%; 473.85±64.35 μm at baseline vs. 470.28±68.18 μm during the VM; P=0.092). In multivariate regression analysis, the mean ALCSD change was greater when the central corneal thickness was thinner in glaucomatous eyes (standardized β value=0.21; P=0.02), whereas that was greater in normal eye when baseline IOP was lower (standardized β value=0.37; P<0.001).Conclusions:
During the VM, the ALCSD was decreased in normal eyes, but was not significantly changed in eyes with treated glaucoma. These results suggest that the physiology of LC displacement in response to IOP and cerebrospinal fluid pressure dynamics might differ between normal and glaucomatous eyes.