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Purpose
To determine the intrascleral location of the circle of Zinn-Haller by simultaneous indocyanine green (ICG) angiography and enhanced-depth imaging optical coherence tomography (EDI-OCT) in highly myopic eyes.
Design
Retrospective, consecutive, observational case series.
Methods
Ninety-four eyes of 67 consecutive patients with pathologic myopia who underwent simultaneous ICG angiography and EDI-OCT examinations by Spectralis HRA-OCT, and whose Zinn-Haller ring was observed within the area of myopic conus by ICG angiography, were studied. The definition of pathologic myopia was a refractive error (spherical equivalent) <?8.00 diopters (D) or an axial length >26.5?mm.
Results
The EDI-OCT images showed cross-sections of the vessels that were identified in the ICG images as the circle of Zinn-Haller. The vessels were seen as a hyporeflective circle within the peripapillary sclera. An intrascleral course of the Zinn-Haller ring was clearly observed in adjacent serial OCT sections. The filling of the Zinn-Haller ring was from the short posterior ciliary arteries, and OCT also showed a continuous pathway from the retrobulbar short posterior ciliary arteries to the circle of Zinn-Haller. Centripetal branches were seen to run toward the optic nerve from the Zinn-Haller ring in 20 eyes by ICG and were confirmed by OCT in 4 eyes.
Conclusions
The HRA-OCT images confirmed that?the vascular structure surrounding the optic disc observed by ICG angiography had topographic features specific to the Zinn-Haller arterial ring by OCT. The in?situ observation of the circle of Zinn-Haller by simultaneous ICG angiography and OCT is a useful method to examine the Zinn-Haller ring in eyes with pathologic myopia.
