Blood pressure and pressure amaurosis

Area of Science:

• Ophthalmology
• Neuroscience
• Physiology

Background:

• Pressure amaurosis is a condition where vision loss occurs due to elevated intraocular pressure.
• The exact relationship between systemic blood pressure and susceptibility to pressure-induced vision loss is not fully understood.

Purpose of the Study:

• To investigate the impact of elevated systemic blood pressure on the threshold for pressure-induced amaurosis.
• To provide further evidence for the hypothesis that pressure amaurosis is caused by neuroretinal ischemia.

Main Methods:

• Young subjects underwent intraocular pressure elevation via paralimbal suction.
• Visual perception of a flickering stimulus was tested at increasing intraocular pressures.
• Systemic blood pressure was elevated using phenylephrine infusions before and during testing.

Main Results:

• A significant correlation was observed between elevated systemic blood pressure and a higher "safe" intraocular pressure limit.
• All subjects demonstrated an increased tolerance to intraocular pressure when their blood pressure was raised.

Conclusions:

• Elevated systemic blood pressure increases the tolerance to intraocular pressure before vision loss occurs.
• These findings support the theory that pressure amaurosis is a consequence of compromised blood flow to the optic nerve (neuroretinal ischemia).