Glaucoma
Conditions
Keywords
Nitrovasodilators, ONH blood flow, Choroidal blood flow, Nitroglycerin, Isosorbide Dinitrate, Sodium nitroprusside, Laser-Doppler Flowmetry, Regional Blood Flow
Brief summary
Glaucoma, one of the most common causes of blindness, is associated with increased intraocular pressure (IOP) and optic nerve head ischemia. Nitrovasodilators are discussed in the treatment of glaucoma. Nitrates relax smooth muscle cells in the vasculature by liberating the vasodilator nitric oxide. The IOP lowering potential and the vasodilator action in retinal and choroidal vessels of nitrates is still a matter of controversy. Previous studies on the ocular hemodynamic effects of nitrates showed partially contradicting results. In addition the IOP lowering effect of nitrates is still unclear. However, recent studies show that long acting nitrates may preserve optic nerve deterioration and visual field loss. Therefore, the role of nitrovasodilators in control of ocular blood flow and intraocular pressure has to be elucidated. For this purpose the investigators plan to test the hypothesis that nitrovasodilators improve ocular blood supply to the optic nerve head at doses which do not affect systemic hemodynamics.
Interventions
DRUGNitroglycerin
intravenous infusion; 0, 0.125, 0.25, 0.5, 1 and 2 µg/kg/min; 20 minutes per infusion step
DRUGIsosorbide-Dinitrate
intravenous infusion; 0, 0.5, 1, 2, 4, and 6 µg/kg/min; 20 minutes per infusion step
intravenous infusion; 0, 0.25, 0.5, 1, 2, and 4 µg/kg/min; 20 minutes per infusion step
DRUGPhysiologic saline solution (control substance)
intravenous infusion, infusion period 120 minutes
Sponsors
Medical University of Vienna
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
MALE
Age
19 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Men aged between 19 and 35 years, nonsmokers * Body mass index between 15th and 85th percentile (Must et al. 1991) * Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant * Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant * Normal ophthalmic findings, ametropia \< 3 Dpt.
Exclusion criteria
* Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study * Treatment in the previous 3 weeks with any drug * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * History of hypersensitivity to the trial drug or to drugs with a similar chemical structure * History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs * History of migraine * Blood donation during the previous 3 weeks
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Optic disc blood flow (laser Doppler flowmetry) | in total 24x on 4 study days |
Secondary
| Measure | Time frame |
|---|---|
| Intraocular pressure | in total 8x in 4 study days |
| Choroidal blood flow (laser Doppler flowmetry) | in total 24x on 4 study days |
| Fundus pulsation amplitude in the macula (laser interferometry) | in total 24x on 4 study days |
| Fundus pulsation amplitude in the optic disc (laser interferometry) | in total 24x on 4 study days |
| Blood pressure, pulse rate | on 4 study days |
Countries
Austria
Outcome results
None listed