Abstract
Purpose:
According to the literature, during moderate Valsalva maneuver (VM) the intraocular pressure (IOP) rises by about 7 mmHg. It generally is assumed that the central retinal vein pressure (CRVP) rises by the same amount. This has not been confirmed. We measured the CRVP directly by contact lens dynamometry (CLD). We hypothesize that CRVP may rise more than the IOP during moderate VM.
Methods:
Prospective, clinical, diagnostic investigation. Subjects: 39 healthy, young volunteers (12 male, 27 female); age: 27±2.6 years (arith.mean±std.dev.). One eye of one subject was examined, OD/OS:19/20. Measurement of IOP by Dynamic Contour Tonometry (DCT). CRVP measurement by CLD (Meditron, Voelklingen, Germany). Sequence of measurements: 1. DCT; 2a. assessment of spontaneous venous pulsation (SVP). If SVP present: CRVP=DCT; 2b. If SVP present: digital oculopression and observation of the central retinal vein until pulsation occurs again. Then DCT-IOP was set as central retinal vein threshold pressure (CRVTP); 2c. If SVP absent: CRVTP measurement by CLD; 3. 2 VM with 3 measurements of the CRVP by CLD; 4. DCT; 5. DCT during VM. Calculation of ΔCRVP=(CRVP during VM)-(spontaneous CRVP).
Results:
SVP present: n=33. Pressures in mmHg. Before VM1: IOP=16.0±2.1, CRVTP=14.4±2.0, CRVP=16.1±2.1. CRVP during VM: VM1: CRVP (mean of 3 measurements)=35.3±7.6, CRVP VM2=31.4±4.1. ΔCRVP VM1=19.2±8.2 (p<0.001), ΔCRVP VM2=15.4±4.4 (p<0.001). IOP after two VMs=13.9±2.0. IOP during VM=14.1±2.4
Conclusions:
The ΔCRVP was significantly higher than the ΔIOP in previous studies during moderate VM. The perfusion pressure, therefore, may be significantly lower during VM than assumed until now.
Keywords: 568 intraocular pressure