Influence of the vasodilator drug isosorbide dinitrate on ocular circulation
V. Hessemer and K. G. Schmidt
Department of Ophthalmology, Justus Liebig University, Giessen, Germany.
OBJECTIVE: To evaluate the ocular hemodynamic effects of the vasodilator
drug isosorbide dinitrate. DESIGN: Randomized, prospective, controlled
clinical trial assessing the short-term effects of 1 tablet containing 40
mg of isosorbide dinitrate vs placebo. SETTING: Department of
Ophthalmology, University of Giessen, Germany. MAIN OUTCOME MEASURES:
Systolic ophthalmic artery pressure (SOAP), systolic ocular perfusion
pressure (SOPP), ocular pulsation amplitude (OPA), product of OPA x heart
rate (HR), intraocular pressure (IOP), systolic and diastolic brachial
artery pressure (SBAP and DBAP). Measurements were performed before and up
to 7 hours after patients received the medication. PARTICIPANTS: Twenty
healthy subjects (mean age, 28 years) who provided informed consent.
RESULTS: After isosorbide dinitrate administration, SBAP, SOAP, and SOPP
were significantly lowered (P = .01), and IOP tended to be lower (P = .08)
compared with placebo. Maximum reduction was 3 to 5 hours after medication:
SBAP was reduced by 10.9 mm Hg (9% reduction; P = .01), SOAP was reduced by
12.5 mm Hg (14% reduction; P = .01), SOPP was reduced by 11.3 mm Hg (14.5%
reduction; P = .01), and IOP by 1.5 mm Hg (12% reduction; P = .08). The
relation between SBAP and SOAP was significantly linear (P < .001), the
correlation coefficient was 0.39. The DBAP remained unchanged, and the HR
increased by 4 to 7/min (P = .08). The OPA and the product OPA x HR were
significantly decreased (P < .001; P = .002) by maximum values of 44%
and 40%, respectively. CONCLUSIONS: Administration of isosorbide dinitrate
reduced SOAP and SOPP, reflecting reduced systemic systolic blood pressure.
The decrease in OPA and the product OPA x HR (a measure of pulsatile ocular
blood flow) may reflect a reduction in cardiac stroke volume typical for
nitrates. Due to these hemodynamic effects and the minute reduction in IOP,
the vasodilator drug isosorbide dinitrate, which has been proposed for
glaucoma therapy, may be used only with caution in patients with glaucoma.
