Peripheral arterial filling time and peripheral retina fluorescence features in ultra-widefield angiography

AIM: To evaluate the peripheral arterial filling time (PAFT) and venous filling time (VFT) in eyes without known diseases that may influence filling process using ultra-widefield (UWF) fluorescein angiography (FA), and to review the peripheral retina fluorescence features. METHODS: A total of 30 eyes of 30 patients were retrospectively reviewed in this observational study. UWF-FA was performed using Optos 200Tx. PAFT and VFT was recorded. The interval between the arterial or venous filling completion and the previous photo was documented. The appearance of the far peripheral retina was described as either granular background fluorescence or mottled fluorescent band or vascular leakage. Terminal vascular patterns was described as loop pattern or branching pattern. Microvascular abnormalities such as arteriovenous shunting, vessels crossing the horizontal raphe, right angle vessels, terminal networks, capillary nonperfusion, drusen or microaneurysms were evaluated. RESULTS: The normal limits of PAFT was 3.397-8.984s and 4.399-11.753s for VFT. The appearance of the far peripheral retina, defined as granular background (63%), mottled fluorescence (20%), or vascular leakage (17%), was symmetrical between both eyes. Capillary nonperfusion (23%) and microaneurysms (40%) were more frequently found in eyes with loop pattern than in eyes with branching pattern. Other peripheral signs such as right-angle vessels (73%), and terminal networks (80%) were commonly seen on UWF-FA in the normal peripheral retina. CONCLUSION: The main courses of retinal artery and vein filling time are overlapping with each other on UWF-FA. Notably, the arterial filling process is completed in the arteriovenous phase rather than the traditionally named arterial phase. There are various manifestations in the peripheral retina of normal eyes.