ORPHEE: ObseRvation of PeripHEral rEtinal morphology in normal eyes

Abstract

Purpose : Purpose: To study the distribution and location of vortex vein ampullae in normal eyes as assessed by ultrawide field indocyanine green angiography (UWF ICGA).

Methods : Thirty six eyes of 36 patients were included in this prospective, IRB-approved study. All patients were 20 years of age or older, and in good general health. A written informed consent was obtained from all the subjects prior to enrolment. The subjects’ demographic data, best corrected visual acuity and detailed ophthalmic exam findings including intra-ocular pressure and axial length were recorded prior to pupillary dilatation. The Optos California (UWF) imaging system was used to capture images following intravenous ICG infusion, using a standardized acquisition protocol. Images were graded by 2 independent, masked certified graders at the Doheny Image Reading Center using the manufacturer’s viewing software, following stereographic projection. A vortex vein ampulla was defined by the presence of a convergence of multiple large choroidal vessels into a single large trunk which appeared to disappear from the eye. The center point of each vortex vein trunk was marked. The number of vortex ampullae and their clock hour position were recorded. The distance from the optic nerve center to the vortex ampulla were measurement using the ruler tool.

Results : Thirty six eyes were included in this study. The mean number of ampullae (as defined by our criteria) observed by UWF ICGA was 7.8 + 2.0 (range 5-13). The mean distance (mm) of a vortex vein ampulla from the optic nerve was 14.38 + 1.23 (10.6-17.7). The mean distance of the ampullae from the optic nerve center in each quadrant is shown in Table 1. The average distance of the ampullae from the optic nerve (mm) in the superior quadrant was 14.08 + 1.05 (10.6 – 17.3), whereas in the inferior quadrant it was 14.74 + 1.47 (11.1 – 17.7). Ampullae were never observed in the 3 O’clock and 9 O’clock meridians. There was excellent inter-grader reproducibility for the distance measurements between graders: ICC = 0.99 (95% CI; 0.979-0.999, P < 0.001)

Conclusions : In this first UWF ICGA study of normal subjects, we observed a larger number of vortex ampulla (>7) than previously thought, and a range of distances (10-18mm) from the optic nerve center in terms of the position of these ampullae. This normative data may serve as a useful references as vortex ampullar abnormalities are evaluated in the setting of diseases.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.