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

The late venous phase of fluorescein angiography is characterized by the full filling of larger veins, which occurs after the initial transit of the dye through the arteries and capillaries. During this phase, the vascular structures within the retina can be evaluated for any abnormalities, such as leakage or staining, which may indicate underlying retinal pathology.

In the late venous phase, the images captured show the slower flow of the dye as it fills and outlines the larger venous structures, allowing technicians to assess the venous system's health and any conditions affecting it, such as retinal vein occlusions or other vascular diseases. This phase typically provides vital information on the condition and integrity of the retinal vasculature, which is pivotal for diagnosing various eye disorders.

The other phases are important but focus on different aspects of blood flow and dye transit. The early venous phase occurs shortly after the arteries are filled but does not show the complete filling of veins. The mid-phase may show some filling of the smaller and medium veins but not to the extent seen in the late phase. Therefore, the indication of full filling of larger veins aligns specifically with the late venous phase of fluorescein angiography.