OCT angiography (OCTA) without dye

Optical Coherence Tomography Angiography (OCTA) is an advanced imaging technique that allows ophthalmologists to visualize blood flow within the delicate blood vessels of the retina and the underlying choroid. Unlike other angiography methods, OCTA does not require intravenous injection of a contrast dye. Instead, it uses light waves to detect subtle changes in blood flow, providing a detailed map of the ocular vasculature.

The primary purpose of an OCTA test is to diagnose and monitor eye conditions that affect the blood vessels in the retina and choroid. It can identify areas of vascular occlusion, the growth of new and abnormal blood vessels (neovascularization), or structural changes in vessels. This information is crucial for accurate diagnosis, treatment planning, and monitoring the effectiveness of therapies for conditions such as age related macular degeneration (AMD), diabetic retinopathy, and retinal vein or artery occlusions. The test does not demonstrate leakage from blood vessels.

The OCTA test is performed while the patient is seated in front of the imaging device. The patient is asked to place their chin and forehead on a support and fix their gaze on a small target light. The machine emits harmless light beams into the eye, scanning it rapidly. Repeated scans allow the device to detect the movement of red blood cells, thereby mapping the blood flow. The test is painless and does not involve direct contact with the eye.

Generally, no special preparation is needed for an OCTA test. In some cases, eye drops may be used to dilate the pupils to improve image quality. If dilation is performed, vision may be blurry for several hours, especially for near vision, and there may be increased light sensitivity. It is advisable to arrange for transportation or avoid driving after the test if pupils are dilated. Head or eye movements during the scan can affect image quality, so it is important to cooperate and remain as still as possible.

OCTA is considered a very safe procedure. It is non invasive, does not involve ionizing radiation, and does not require contrast dye injection, thus avoiding the risks associated with allergic reactions to contrast agents. However, image quality can be affected by conditions such as advanced cataracts, intraocular hemorrhage, or the patient's inability to maintain steady fixation. In certain situations, additional imaging tests, such as fluorescein angiography (FA) or indocyanine green (ICG) angiography, may be necessary to obtain complementary information, especially for evaluating vascular leakage.

The images obtained from an OCTA test are analyzed by the ophthalmologist, who integrates the findings with the patient's medical history, symptoms, and results from other eye examinations. OCTA provides unique information about blood flow, but each imaging modality has its own advantages and limitations. The doctor will determine the clinical significance of the findings and recommend an appropriate treatment or follow up plan, tailored to the patient's specific condition.