Zinn-Haller arterial ring observed by ICG angiography in high myopia

Aims - To delineate the entire Zinn-Haller arterial ring angiographically i n vivo. Methods - 382 highly myopic eyes (210 patients) with refractive errors grea ter than -8.25 D were examined using indocyanine green (ICG) videoangiograp hy. A control group of 80 eyes (40 patients) had refractive errors within p iano +/- 3 D. Results - The Zinn-Haller ring was visible in 206 of 382 highly myopic eyes (53.9%) by ICG angiography. Although only a part of the Zinn-Haller ring w as visible in 162 of 206 eyes, in the remaining 44 eyes it was observed alm ost completely around the optic nerve head. No anastomotic channels between lateral and medial short posterior ciliary arteries were filled by ICG ang iography. In 22 of the 44 eyes (50.0%) the Zinn-Haller ring was supplied by branches of the lateral and medial short posterior ciliary arteries; in se ven eyes, it was supplied only by the lateral short posterior ciliary arter y; and in seven eyes, it was supplied only by the medial short posterior ci liary artery. In none of the control subjects was the Zinn-Haller ring visi ble by ICG angiography. Conclusions - The Zinn-Haller ring observed by ICG angiography was not a co mplete collateral circle between lateral and medial posterior ciliary arter ies. Also, the patterns in supply vessels to the Zinn-Haller ring varied. I CG angiography made possible the detailed observation of the Zinn-Haller ri ng in human eyes in vivo.