Certified Ophthalmic Technician (COT) Practice Test 2026 - Free COT Practice Questions and Study Guide

The earliest phase of retinal circulation in fluorescein angiography is characterized by the visualization of the arterial supply to the retina following the intravenous injection of fluorescein dye. In this arterial phase, which occurs within the first few seconds after injection, the dye quickly travels through the retinal arteries, allowing practitioners to observe the perfusion of the retinal tissues. This phase is critical for evaluating the blood flow to the retina and identifying any potential abnormalities or blockages in the arteries.

The arterial phase provides important diagnostic information, as it is during this phase that the initial patterns of vascular distribution are evident. This contrasts with other phases of fluorescein angiography, which occur later in the sequence. For instance, the venous phase depicts the filling of the retinal veins after the arteries, occurring after the arterial phase. The mid-phase and late phase occur subsequently and provide different views and insights into retinal vascular health, but the arterial phase is the starting point in assessing the retinal circulation.