Ocular Blood Flow In Patients Research Articles

Effect of dorzolamide timolol combination versus timolol 0.5% on ocular bloodflow in patients with primary open-angle glaucoma

PURPOSE: Addition of dorzolamide to timolol in primary open-angle glaucoma shows augmented reduction of intraocular pressure. It is unknown as yet if addition of dorzolamide will alter hemodynamics. METHODS: Fifteen patients with primary open-angle glaucoma were placed on a medication-dependent 1-week to 4-week washout that included maintenance on timolol. After washout, baseline measurements were taken (timolol). They were studied after a month on timolol or dorzolamide-timolol (Cosopt®; Merck, Inc, Whitehouse Station, New Jersey), with the second drug preceded by another month of timolol maintenance and second baseline measurements. At each visit, visual function, intraocular pressure, and ocular hemodynamics were monitored, including indocyanine green and fluorescein angiography and color Doppler imaging. RESULTS: Cosopt® significantly reduced intraocular pressure (14.7 to 13.4 mm Hg, P < .05) and increased arteriovenous passage time (superior temporal artery) of fluorescein dye (2.13 to 1.76 seconds, P = .01) but had no effect on visual function. CONCLUSIONS: When compared with timolol in primary open-angle glaucoma, Cosopt® augments ocular tension reduction and reduces the amount of time required for blood to pass through the superior retinal vasculature.

Acute and chronic effects of brimonidine 0.2% on intraocular pressure and pulsatile ocular blood flow in patients with primary open-angle glaucoma: an open-label, uncontrolled, prospective study

Background: Brimonidine has been reported to decrease aqueous production and increase uveoscleral outflow; however, the hemodynamic effects of brimonidine are still under investigation. Objective: The purpose of this study was to report the acute and chronic effects of brimonidine 0.2% on intraocular pressure (IOP) and pulsatile ocular blood flow (pOBF) in patients with primary open-angle glaucoma (POAG). Methods: Nonsmoking patients aged 45 to 67 years with POAG and normal blood pressure, heart rate, body mass index, and hemorheologic parameters were enrolled in the study. Brimonidine 0.2% was self-administered twice daily for 180 days. IOP and pOBF were determined using Goldmann applanation tonometry and the Langham system. All measurements were taken at baseline and 4, 8, and 12 hours after treatment and were repeated on days 7, 15, 30, 60, 90, 120, 150, and 180 of treatment. Results: Of the 18 eligible patients, 10 (6 men and 4 women) were enrolled (mean age, 51.5 ± 4.39; range, 47–64 years). When measured 12 hours after instillation, mean IOP was significantly reduced by 21.5% ( P < 0.001) compared with the baseline value. The greatest decrease in IOP (−23.5%) was observed at 8 hours. After 12 hours, a significant increase ( P < 0.001) in pOBF was measured. A stable IOP reduction ( P < 0.001 vs baseline), as well as an increase in pOBF ( P = 0.015), was recorded at the subsequent time points. The pOBF increases ranged from 22.5% at day 30 to 9.2% at day 180 of treatment. No evidence of adverse events was found at any time point. Conclusions: In this sample of patients with open-angle glaucoma, brimonidine induced a rapid reduction in IOP that was significant even after 6 months. Moreover, an increase in pOBF was observed from the first day of treatment, and remained consistent throughout the study.

Pulsatile ocular blood flow in patients with pseudoexfoliation.

Pseudoexfoliation syndrome is one of the most frequent causes of open-angle glaucoma and is statistically significant associated with a high risk of hypertension, angina, myocardial infarction or stroke and retinal vein thrombosis. The aim of this study was to evaluate the pulsatile ocular blood flow (POBF) in pseudoexfoliation syndrome without (PEX) and with glaucoma (PEG). Seventeen eyes with PEX, 17 with PEG and 11 normal eyes of age-matched patients were enrolled. A complete ophthalmological examination included measuring the POBF with the Langham Pneumotonometer as well as the nerve fiber layer thickness by scanning laser polarimetry (GDx). The blood flow parameters, pulse volume and POBF, were statistically significant different between normals and patients with PEG (p < 0.003, t-test). A negative correlation between the intraocular pressure and the POBF was found for all eyes tested. Analysis of GDx? parameters showed a negative correlation for the "number" with the POBF and a positive one for ellipse modulation. Although pseudoexfoliation is reported to be a systemic disease measurement of the POBF could not detect any difference between normals and PEX, but was statistically significant different in PEG. Assessments of nerve fiber layer thickness as determined by scanning laser polarimetry also showed a correlation with POBF in some parameters tested.

Effect of small incision cataract surgery on ocular blood flow in cataract patients

Purpose To evaluate the effect of small incision cataract surgery using peribulbar anesthesia on ocular blood flow in patients with senile cataract. Setting Department of Ophthalmology, University of Vienna, Vienna, Austria. Methods In 33 eyes of 33 consecutive patients scheduled for cataract surgery, ocular hemodynamics were measured preoperatively and 1 day, 1 week, and 1 month postoperatively. Measurements included fundus pulsation amplitude (FPA) with a laser interferometric method that assessed the pulsatile choroidal blood flow, mean blood flow velocity (MFV), and resistive index (RI) in the ophthalmic artery (OA) and the central retinal artery (CRA) with Doppler sonography. Systemic hemodynamics and intraocular pressure (IOP) also were measured. Results The FPA, MFV, and RI in the OA and the CRA did not change postoperatively from baseline values. Systemic hemodynamics, IOP, and as a consequence ocular perfusion pressure, also remained unchanged. Conclusion Uneventful small incision cataract surgery using peribulbar anesthesia did not affect ocular blood flow in patients with senile cataract between 1 day and 1 month postoperatively.

Effects of peribulbar anesthesia on ocular blood flow in patients undergoing cataract surgery

PURPOSE: The effects of extraconal, peribulbar anesthesia on ocular blood flow may be caused by concomitant elevations in intraocular pressure or direct pharmacologic alteration of vascular tone. We quantified the effect on ocular circulation with a new technique for assessment of ocular hemodynamics. METHODS: In a prospective study, ocular hemodynamics were measured before and 1 and 5 minutes after peribulbar anesthesia in 22 eyes with age-related cataract. Measurements included fundus pulsation amplitude with a laser interferometric method assessing the pulsatile choroidal blood flow and mean blood flow velocity as well as resistive index in the ophthalmic and central retinal artery with Doppler sonography. Systemic blood pressure and pulse were monitored throughout the period of ocular hemodynamic measurements. RESULTS: Fundus pulsation amplitude decreased significantly after peribulbar anesthesia (after 1 minute and 5 minutes: −13% and −8%; P< .001). In the central retinal artery, mean blood flow velocity dropped (−15%; P < .001) and resistive index increased (+3%; P = .02) 1 minute after peribulbar anesthesia compared with baseline. There were no changes in ophthalmic artery hemodynamics. Intraocular pressure was elevated 1 minute after peribulbar anesthesia (+29%; P = .003) but reached baseline values after 5 minutes. CONCLUSION: Pulsatile choroidal blood flow and retinal blood flow velocities were reduced after peribulbar anesthesia. These reductions were still present 5 minutes after peribulbar anesthesia, when intraocular pressure had returned to baseline values. This supports the theory of drug-induced vasoconstriction after peribulbar anesthesia. A loss of vision may be a risk of peribulbar anesthesia in patients who have compromised ocular blood flow before surgery.

Nitric oxide and ocular blood flow in patients with IDDM

Nitric oxide and ocular blood flow in patients with IDDM

Effect of oral nifedipine on ocular blood flow in patients with low tension glaucoma.

To investigate the effect of oral nifedipine on ocular blood flow in patients with low tension glaucoma (LTG). In this prospective study we examined the effects of 3 weeks of treatment with oral nifedipine 30 mg/day in 11 patients with LTG, by using colour Doppler ultrasound imaging to measure haemodynamic variables in the central retinal (CRA), short posterior ciliary (SPCA), and ophthalmic (OA) arteries. Intraocular pressure (IOP) and blood pressures were also evaluated. Nifedipine failed to alter IOP nor did it change peak systolic velocity, end diastolic velocity,or the resistance index in any of the three ocular vessels studied (p > 0.05). However systolic and diastolic systemic arterial blood pressure measurements varied significantly after nifedipine treatment compared with baseline (p < 0.05). Our study failed to demonstrate a significant effect of nifedipine on retrobulbar circulation of patients with LTG.

Effects of pentoxifylline on choroidal blood flow in nonproliferative diabetic retinopathy.

Diminished blood flow plays an important role in the progression of diabetic retinopathy. Since increased blood viscosity is a contributing factor to hypoperfusion, it was of interest to determine whether therapy intended to decrease blood viscosity and induce vasodilation could increase blood flow in patients with diabetic retinopathy. Ten patients, 4 with nonproliferative diabetic retinopathy and 6 age-matched, nondiabetic controls, were studied by a noninvasive system to index choroidal blood flow. Pentoxifylline was administered daily at an oral dose of 400 mg tid in the diabetic patients for nine months. The control group had pulse amplitude = 2.87 +/- 0.67 mm Hg with pulsatile choroidal blood flow = 714 +/- 196 microL/minute. Reproducibility studies in the control group (6 patients measured on three separate occasions) demonstrated an intraclass correlation coefficient of reliability, r = 0.83. In the diabetic patients, pulsatile flow = 276 +/- 68 microL/minute, 61% lower than the age-matched nondiabetic subjects (P = 0.003). After nine months of pentoxifylline therapy the diabetic patients had an increase in pulsatile choroidal blood flow to 469 +/- 152 microL/minute (P < 0.002). Pentoxifylline therapy brought blood flow levels in the diabetic patients closer to those of the nondiabetic age-matched control population so that following therapy there was no statistically significant difference between the two groups although the former were still lower. The potential efficacy of pentoxifylline in improving ocular blood flow in patients with diabetic retinopathy should be tested in a large controlled clinical trial.

Effects of Pentoxifylline on Choroidal Blood Flow in Nonproliferative Diabetic Retinopathy

Objective: Diminished blood flow plays an important role in the progression of diabetic retinopathy. Since increased blood viscosity is a contributing factor to hypoper fusion, it was of interest to determine whether therapy intended to decrease blood viscosity and induce vasodilation could increase blood flow in patients with diabetic retinopathy Methodology: Ten patients, 4 with nonproliferative diabetic retinopathy and 6 age- matched, nondiabetic controls, were studied by a noninvasive system to index choroidal blood flow. Pentoxifylline was administered daily at an oral dose of 400 mg tid in the diabetic patients for nine months. Results: The control group had pulse amplitude=2.87 ± 0.67 mm Hg with pulsatile choroidal blood flow=714 ± 196 μL/minute. Reproducibility studies in the control group (6 patients measured on three separate occasions) demonstrated an intraclass correlation coefficient of reliability, r=0.83. In the diabetic patients, pulsatile flow=276 ± 68 μL/minute, 61% lower than the age-matched nondiabetic subjects (P=0.003). After nine months of pentoxifylline therapy the diabetic patients had an increase in pulsatile choroidal blood flow to 469 ± 152 μL/minute (P &lt; 0.002). Conclusions: Pentoxifylline therapy brought blood flow levels in the diabetic patients closer to those of the nondiabetic age-matched control population so that following therapy there was no statistically significant difference between the two groups although the former were still lower. The potential efficacy of pentoxifylline in improving ocular blood flow in patients with diabetic retinopathy should be tested in a large controlled clinical trial.