Distribution and Location of Vortex Vein Ampullae in Healthy Human Eyes as Assessed by Ultra-Widefield Indocyanine Green Angiography

Purpose: To study the number and distribution of vortex ampullae in healthy eyes using ultra-wide field (UWF) indocyanine green angiography (ICGA).

Design: Prospective, observational study.

Participants: Thirty-six eyes of 36 healthy participants with no evidence of ocular or systemic disease.

Methods: The UWF ICGA images (central and peripheral steered) were captured using the Optos California (Optos, Dunfermline, United Kingdom) instrument. The images were projected stereographically to correct for peripheral distortion and obtain accurate measurements. All images were graded and analyzed for number, location, and distance of the vortex vein ampullae from the center of optic nerve.

Main outcome measures: Mean number and the distance of ampullae from the center of optic nerve in all quadrants.

Results: The mean number of ampullae observed by UWF ICGA was 8.0±2.1 (range, 5-13). The mean distance of a vortex vein ampulla from the optic nerve was 14.2±1.1 mm (range, 10.3-17.7 mm). The frequency of ampullae was higher in the superior and inferior quadrants than the nasal and temporal quadrants. Ampullae were never observed in the 3- or 9-o'clock meridians. Multiple regression analysis showed no relationship with age, gender, axial length, or ethnicity. Excellent intergrader reproducibility was found between graders with an intraclass correlation coefficient (distance measurements: intraclass correlation coefficient, 0.99; 95% CI, 0.979-0.999; P < 0.001; number of ampullae: intraclass correlation coefficient, 0.99; 95% CI, 0.988-0.999; P < 0.001).

Conclusions: The number of discrete vortex vein ampullae that can be discerned by UWF ICGA in healthy individuals is greater frequently and substantially than the 4 that are traditionally thought to drain the major quadrants. Considerable variability in the number and position of the ampullae may be apparent in healthy individuals.