Abstract
Purpose:
To assess whether a Valsalva maneuver influences intraocular pressure (IOP), cerebrospinal fluid pressure (CSF-P) and, by a change in the trans-laminar cribrosa pressure difference, optic nerve head morphology.
Methods:
The study included 20 neurological patients who required lumbar puncture and 20 healthy volunteers. In a first study part, neurological patients underwent measurement of IOP and lumbar CSF-P measurement in a lying position before and during a Valsalva maneuver with a documented continuous expiratory pressure of ≥30 mmHg for about 20 seconds. In the second part, 20 healthy subjects underwent ocular tonometry and confocal scanning laser tomography of the optic nerve head before and during a Valsalva maneuver.
Results:
During the Valsalva maneuver in the first study part, the increase in CSF-P by 10.5±2.7 mmHg was significantly (P<0.001) higher than the increase in IOP by 1.9±2.4 mmHg. The change in CSF-P was not significantly (P=0.61) correlated with the change in IOP. During the Valsalva maneuver in the second part, IOP increased by 4.5±4.2 mmHg and optic cup volume (P<0.001), cup/disc area ratio (P=0.04), cup/disc diameter ratio (P=0.03) and maximum optic cup depth (P=0.02) significantly decreased, while neuroretinal rim volume (P=0.003) and mean retinal nerve fiber layer thickness (P=0.02) significantly increased.
Conclusions:
The Valsalva maneuver-associated increase in CSF-P was significantly larger than, and not correlated with, and a simultaneous increase in IOP. This Valsalva maneuver associated reversal of the trans-lamina cribrosa pressure difference resulted in a change of the three-dimensional optic nerve head morphology with a decrease in optic cup related parameters and an enlargement of neuroretinal rim related parameters. These findings may be relevant to the pathogenesis of glaucomatous optic neuropathy.
Keywords: 627 optic disc •
550 imaging/image analysis: clinical •
577 lamina cribrosa