The Distribution of Retinal Venous Pressure and Intraocular Pressure Differs Significantly in Patients with Primary Open-Angle Glaucoma.

INTRODUCTION: Until now, venous pressure within the eye has widely been equated with intraocular pressure (IOP). Measurements with dynamometers calibrated in instrument units or in force showed that the retinal venous pressure (RVP) may be higher than the IOP in glaucoma patients. In this study, the RVP was measured with a contact lens dynamometer calibrated in mmHg. METHODS: Study type: cross-sectional. SUBJECTS: Fifty consecutive patients with primary open-angle glaucoma (POAG) who underwent diurnal curve measurement under medication. Age: 69 ± 8 years. Measurement of RVP: contact lens dynamometry. IOP measurement: dynamic contour tonometry. RESULTS: Pressures are given in mmHg. In all 50 patients, the IOP was 15.9 (13.6; 17.1) [median (Q1; Q3)], and the RVP was 17.4 (14.8; 27.2). The distribution of the IOP was normal and that of the RVP was right skewed. In the subgroup of 34 patients with spontaneous pulsation of the central retinal vein (SVP), the IOP and therefore, by definition, the RVP was 16.5 (13.7; 17.4). In the subgroup of 16 patients without SVP, the IOP was 14.8 (13.3; 16.4), and the RVP was 31.3 (26.2; 38.8) (p ≤ 0.001). In systemic treatment, the prescribed drugs were (the number of patients is given in parentheses): ACE inhibitors (20), ß-blockers (17), angiotensin II-receptor blockers (13), calcium channel blockers (12), diuretics (7). No difference in RVP was observed between patients receiving these drugs and not receiving them, except in the ß-blocker group. Here, the 17 patients with systemic ß-blockers had a median RVP of 15.6 mmHg and without 20.2 mmHg (p = 0.003). In the 16 patients with a higher RVP than IOP, only one patient received a systemic ß-blocker. The median IOP was 15.7 mmHg with systemic ß-blockers and 16.1 mmHg without (p = 0.85). CONCLUSION: In a subgroup of 16 of the 50 patients studied, the RVP was greater than the IOP by a highly statistically and clinically significant degree. According to the widely accepted thinking on the pathophysiology of retinal and optic nerve head circulation, the blood flow in these tissues may be much more compromised in this group of patients than has been assumed. They may be identified by a missing SVP. Topical and systemic medications showed no statistically significant influence on the RVP, except for the systemic ß-blockers, in which the RVP was lower by 4.6 mmHg than for the patients who did not receive these drugs (p = 0.003).

Central retinal venous pressure is higher than intraocular pressure during amateur trumpet playing.

BACKGROUND: It has been shown in the literature that the Valsalva manoeuvre influences ocular perfusion by changing intraocular pressure and central retinal venous pressure (CRVP). High-resistance wind instrument (HRWI) playing is a common situation resembling a Valsalva manoeuvre. The aim of this investigation was to explore the influence of amateur trumpet playing on CRVP. METHODS: The left eyes of 20 healthy non-professional trumpet players (median age 26, range 19-52 years; 17 males, 3 females) were included in this investigation. Subjects, sitting at a slit lamp, were asked to play the tone b' flat with their own mouthpiece on the same trumpet for at least 30 s with moderate loudness. The following data were obtained: intraocular pressure (IOP) by applanation tonometry before and during playing, CRVP by contact lens dynamometry before and during playing, airway pressure (AirP) using a pressure sensor during playing and blood pressure and heart rate using the common cuff method before and during playing. RESULTS: The results are presented as the medians before vs during playing: a calculated mean ophthalmic artery pressure of 66 vs 72 mmHg, heart rate of 76 vs 82 beats per minute, airway pressure of 0 vs 17 mmHg, IOP 12 vs 13 mmHg and CRVP of 24 vs 55 mmHg (Wilcoxon test: p = 0.00009), respectively. A correlation between the CRVP during playing and the height of the spontaneous CRVP is noted (Spearman rank correlation coefficient: ρ = 0.68). CONCLUSIONS: Amateur trumpet playing increases CRVP, airway pressure and IOP. The increase in CRVP is greater than that of the intraocular pressure. The increase in CRVP seems to be more important for retinal perfusion changes during trumpet playing than the increase of IOP. It can be hypothesised that high airway pressure during playing may cause a permanent increase in CRVP, at least in a subgroup of trumpet players.

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

PURPOSE: 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). METHODS: 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. RESULTS: 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). CONCLUSION: 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.