Watershed zone in the human peripheral choroid

Area of Science:

• Ophthalmology
• Vascular Biology
• Anatomy

Background:

• The choroid, a vascular layer of the eye, provides nourishment to the outer retina.
• Understanding the angioarchitecture of the peripheral choroid is essential for diagnosing and treating various ocular conditions.

Purpose of the Study:

• To investigate the angioarchitecture and hemodynamics of the peripheral choroid in humans.
• To identify any potential watershed zones in the peripheral choroidal vasculature.

Main Methods:

• Wide-angle indocyanine green (ICG) angiography was performed using a scanning laser ophthalmoscope.
• A specialized lens expanded the field of view to capture the peripheral temporal choroid and ora serrata.
• The study included 23 normal eyes and 7 eyes with equatorial lattice degeneration.

Main Results:

• A distinct arterial watershed zone was identified in the temporal peripheral choroid of 21 out of 30 eyes.
• This watershed zone was located posterior to the ora serrata and did not form an equatorial ring.
• The peripheral retrograde choroidal arteries, supplying the area anterior to the watershed, originated from long posterior ciliary arteries or anterior ciliary arteries.

Conclusions:

• A peripheral watershed zone is a consistent finding in the far temporal choroid.
• The far peripheral choroid anterior to this zone is perfused by peripheral retrograde choroidal arteries.
• No correlation was found between the watershed zone and equatorial lattice degeneration.