Fluorescein angiography (FA) has long been the gold standard for vascular imaging of the retina and choroid. It is a test that involves the intravenous injection of fluorescein dye, followed by imaging of the dye's passage through the blood vessels inside the eye. It is commonly used to diagnose many forms of retinovascular disease, as well as to assess the retina's response to various therapeutic interventions. While FA is a relatively safe diagnostic test, it carries the risk of both minor and major side effects. These include nausea and vomiting, yellowing of the skin and urine, vascular extravasation with skin eruption and necrosis, vasovagal reactions, myocardial infarction, respiratory failure, anaphylaxis, cardiopulmonary arrest, and death. Additionally, the test is time-consuming, technically difficult to perform, and requires patients to undergo the discomfort associated with intravenous access. Despite these drawbacks, FA is still commonly used in clinical practice, as there are no existing alternative tests with the ability to provide comparable detail of the retinal and choroidal vasculature.
Phase-variance optical coherence tomography is a novel, noninvasive, software-based technology capable of generating angiographic images from the data gathered by standard OCT scans. Preliminary research suggests it can produce high-definition representations of the retinal and choroidal vasculature which may be more detailed than the images produced by FA.
