Effect of ocular pressure on choroidal circulation in the cat and Rhesus monkey

Area of Science:

• Ophthalmology
• Vascular Physiology
• Ocular Circulation

Background:

• The choroid is a vascular layer in the eye responsible for supplying nutrients and oxygen to the retina.
• Understanding choroidal blood flow regulation is crucial for diagnosing and treating various ocular diseases.
• Previous research has explored factors influencing ocular blood flow, but the passive nature of the choroidal vasculature under elevated pressure remained unclear.

Purpose of the Study:

• To investigate the effect of elevated ocular pressure on choroidal blood flow rate.
• To determine if the choroidal vascular bed exhibits active regulation in response to changes in intraocular pressure.

Main Methods:

• Utilized the heated thermocouple principle to measure blood flow rate in the choroid.
• Experimentation conducted on anesthetized cats and Rhesus monkeys.
• Ocular pressure was systematically elevated to observe its impact on choroidal circulation.

Main Results:

• An increase in ocular pressure was found to significantly reduce blood flow rate in the choroidal circulation.
• The magnitude of this reduction correlated with the level of ocular pressure applied.
• No evidence of active vascular regulation was observed in the choroidal bed under the tested conditions.

Conclusions:

• The choroidal vascular bed in cats and Rhesus monkeys functions as a passive system.
• Elevated ocular pressure directly impedes choroidal blood flow without compensatory active mechanisms.
• These findings have implications for understanding the pathophysiology of ocular conditions affected by intraocular pressure.