Retinal venous pressure is higher than the airway pressure and the intraocular pressure during the Valsalva manoeuvre.

The aims of this prospective experimental study were to explore the influence of the Valsalva manoeuvre (VM) on retinal venous pressure (RVP) in human volunteers in a university setting and to establish correlations for RVP with the increase in airway pressure (∆AirP) and in intraocular pressure (∆IOP).In total, 31 healthy young volunteers (age: 24 ± 1.7 years) were investigated. The instruments used included a dynamic contour tonometer, a contact lens dynamometer (Imedos) and an electronic pressure transducer for measuring airway pressure. The following measurements were successively performed in left eyes: tonometry, dynamometry, repeated simultaneous dynamometry and airway pressure measurement during the VM and tonometry during the VM. The pressures obtained during the VM were determined at 10, 20 and 30 seconds after onset of the VM by linear interpolation.The pressures (in mmHg) at baseline and during the VM (median and range with outliers) were as follows: ∆AirP: 10 seconds: 10.0 (7.5); 20 seconds: 12.5 (11.0); and 30 seconds: 11.0 (10.0); and RVP: Start: 17.1 (2.4); 10 seconds: 26.0 (7.5); 20 seconds: 25.0 (6.5); and 30 seconds: 24.0 (6.0). During the VM, the RVP was significantly increased compared with the ∆AirP (p = 0.0017). The IOP during the VM was 13.5 (2.7), and the increase in IOP (∆IOP) was 0.8 (5.6).During the VM, the RVP was increased compared with the ∆AirP. The increase in RVP (∆RVP) was significantly greater than the ∆IOP. During the VM, the calculated retinal perfusion pressure may be more strongly reduced by the ∆RVP than by the ∆IOP. These properties may influence retinal and optic nerve head pathophysiology.