[Effect of the vasodilator isosorbide dinitrate on ocular circulation]

Area of Science:

• Ophthalmology
• Cardiovascular Physiology
• Pharmacology

Background:

• Vasodilator drugs are being explored for glaucoma treatment.
• Isosorbide dinitrate (ISDN) is a vasodilator drug with potential antiglaucomatous properties.

Purpose of the Study:

• To evaluate the hemodynamic effects of isosorbide dinitrate (ISDN).
• To determine the suitability of ISDN for glaucoma therapy based on hemodynamic parameters.

Main Methods:

• A randomized trial involving 20 healthy subjects.
• Administration of ISDN (40 mg) or placebo with an analgesic.
• Measurement of ophthalmic artery pressure (SOAP), ocular perfusion pressure (SOPP), intraocular pressure (IOP), and brachial artery pressure (SBAP) at various time points using oculo-oscillo-dynamography.

Main Results:

• ISDN significantly reduced systolic brachial artery pressure (SBAP), systolic ophthalmic artery pressure (SOAP), and systolic ocular perfusion pressure (SOPP).
• A trend towards lower intraocular pressure (IOP) was observed with ISDN.
• ISDN caused significant decreases in ocular pulsation amplitude (OPA) and pulsatile ocular blood flow (OPA x HR).

Conclusions:

• ISDN reduces ocular blood flow parameters (SOAP, SOPP) primarily due to decreased systemic blood pressure.
• The observed decrease in ocular pulsation amplitude (OPA) suggests a reduction in cardiac stroke volume.
• ISDN's hemodynamic effects and minimal IOP reduction indicate it is not suitable for glaucoma therapy.