Detection of Zinn-Haller arterial ring in highly myopic eyes by simultaneous indocyanine green angiography and optical coherence tomography.

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.