Purpose:
Unrecognized elevations of intraocular pressure (IOP) during hemodialysis (HD) could lead to glaucomatous optic nerve damage and visual loss. Ocular perfusion pressure (OPP) has also been demonstrated as a risk factor for glaucoma. The Barbados Eye Studies provided incidence data demonstrating low OPP at baseline had increased risk of development of glaucoma compared with those with higher pressures, with different relative risks for systolic, diastolic, and mean OPP. As few studies have investigated OPP changes with HD, we aimed to examine changes in IOP and OPP during HD and assess correlation between IOP & OPP with parameters including plasma osmolarity and colloid osmotic pressure.
Methods:
49 patients undergoing HD were enrolled. At 3 time points, IOP was measured using a pneumatonometer (Model 30 Classic, Mentor®, Reichart, Buffalo, NY), and systemic blood pressure was recorded. The time points were as follows: T1: upright, approximately 15 minutes prior to start of HD; T2: upright, 2 hours after HD started; T3: upright, approximately 15 minutes after HD ended. OPP was calculated using: OPP = MAP - IOP. Systolic OPP (SOPP), diastolic OPP (DOPP), and mean OPP (MOPP) were also derived.
Results:
Using parametric paired t-tests, mean IOP increased 1.9 mmHg OD and 1.4 mmHg OS from T1 to T2. IOP increased 1.2 mmHg OD & 1.6 mmHg OS from T2 to T3. IOP at T3 was on average 3.1 mmHg higher than T1 in both eyes. OPP, SOPP, DOPP, and MOPP were all found to be significantly decreased at T2 and T3 compared to baseline values. See table 1. Furthermore, during T1 to T3, 22.4% of OD and 20.8% of OS had an OPP less than 55 mmHg. There were no significant correlations between changes in IOP or OPP with changes in plasma osmolarity, rate of change in plasma osmolarity, changes in colloid osmotic pressure, dialysis rate, volume of ultrafiltrated fluid, & changes in body weight.
Conclusions:
This study demonstrates significant increases in IOP and decreases in OPP during hemodialysis to a level that has been reported to interfere with autoregulation, suggesting that certain populations may be susceptible to optic nerve damage and visual loss, especially worrisome in that these patients are chronically exposed to these OPP changes during hemodialysis sessions, at a frequency of three times weekly.
Keywords: intraocular pressure