Ocular blood flow in phakic and aphakic monkey eyes

Area of Science:

• Ophthalmology
• Ocular Physiology
• Pharmacology

Background:

• Topical epinephrine is used to treat glaucoma.
• Epinephrine has been linked to aphakic cystoid macular edema.

Purpose of the Study:

• To investigate the effects of topical epinephrine on regional ocular blood flow in phakic and aphakic primate eyes.
• To determine the temporal profile of these blood flow alterations.

Main Methods:

• Radioactive microsphere technique with three isotopes for sequential measurements.
• Study conducted on Macaca arctoides (primate model).
• Blood flow measured at baseline, 1 hour, and 3 hours post-epinephrine administration.

Main Results:

• Significant reductions in ocular blood flow observed in the iris, ciliary body, and optic nerve head in both phakic and aphakic eyes.
• Aphakic eyes exhibited additional significant decreases in choroidal and posterior optic nerve flow.
• Blood flow reductions were maximal at 3 hours post-administration.
• No significant changes in retinal blood flow were detected.

Conclusions:

• Topical epinephrine causes significant regional ocular hypoperfusion.
• Findings suggest potential risks associated with epinephrine use, particularly in aphakic eyes.
• Further research is needed to clarify the role of epinephrine in cystoid macular edema and its suitability for glaucoma treatment.