Valsalva manoeuver, intra‐ocular pressure, cerebrospinal fluid pressure, optic disc topography: Beijing intracranial and intra‐ocular pressure study

Abstract

To assess whether a Valsalva manoeuver influences intra-ocular pressure (IOP), cerebrospinal fluid pressure (CSF-P) and, by a change in the trans-laminar cribrosa pressure difference, optic nerve head morphology. In the first part of the study, 20 neurological patients (study group 'A') underwent measurement of IOP and lumbar CSF-P measurement in a lying position before and during a Valsalva manoeuver. In the second study part, 20 healthy subjects (study group 'B') underwent ocular tonometry and confocal scanning laser tomography of the optic nerve head before and during a Valsalva manoeuver. During the Valsalva manoeuver in study group 'A', the increase in CSF-P by 10.5±2.7mmHg was significantly (p<0.001) higher than the increase in IOP by 1.9±2.4mmHg. The change in CSF-P was not significantly (p=0.61) correlated with the change in IOP. During the Valsalva manoeuver in study group 'B', IOP increased by 4.5±4.2mmHg and optic cup volume (p<0.001), cup/disc area ratio (p=0.02), cup/disc diameter ratio (p=0.03) and maximum optic cup depth (p=0.01) significantly decreased, while neuroretinal rim volume (p=0.005) and mean retinal nerve fibre layer thickness (p=0.02) significantly increased. The Valsalva manoeuver-associated short-term increase in CSF-P was significantly larger than a simultaneous short-term increase in IOP. It led to a Valsalva manoeuver-associated decrease or reversal of the trans-laminar cribrosa pressure difference, which was associated with a change in the three-dimensional optic nerve head morphology: optic cup-related parameters decreased and neuroretinal rim-related parameters enlarged. These findings may be of interest for the pathogenesis of glaucomatous optic neuropathy.