OCT, Angiography, and Widefield Imaging: Retinal Tests Explained

Thirty years ago, diagnosing a retinal condition depended almost entirely on what the doctor could see through a lens. Today, imaging shows the retina at near-microscopic resolution in seconds — and it is a large part of why outcomes have improved so much.

Optical Coherence Tomography (OCT)

OCT uses light waves to build a cross-sectional image of the retina, layer by layer, with resolution measured in microns. It is the single most important test in retinal care.

What it shows: Fluid under or within the retina, macular thickness, drusen, macular holes, epiretinal membranes, and the integrity of individual retinal layers.

What it feels like: You rest your chin on a support and look at a target for a few seconds per eye. No contact, no dye, no discomfort. Dilation is often but not always needed.

Why it is repeated: Comparing scans across visits is how we decide whether an injection is due, whether treatment intervals can be extended, and whether a condition is progressing.

OCT Angiography (OCTA)

A software-driven extension of OCT that maps blood flow in the retinal and choroidal circulation without any injected dye. Useful for detecting abnormal new vessels in AMD and areas of poor perfusion in diabetes.

Fluorescein Angiography

A yellow dye is injected into a vein in your arm and photographed as it circulates through the retina over several minutes. It remains the gold standard for mapping leakage, blockage, and abnormal vessels.

What to expect: A brief warm flush and occasional nausea as the dye enters. Your skin may look slightly yellow and your urine bright orange for a day — both normal. Allergic reactions are uncommon; tell us about any prior dye reaction.

Indocyanine Green Angiography

Similar in principle but uses a dye that images the deeper choroidal circulation. Reserved for specific conditions such as polypoidal disease and central serous retinopathy.

Fundus Photography and Widefield Imaging

High-resolution color photographs document the retina for comparison over time. Widefield and ultra-widefield systems capture far more of the peripheral retina in a single image, which matters for diabetic retinopathy, vein occlusions, and peripheral tears.

Fundus Autofluorescence

Captures the natural fluorescence of retinal pigment metabolic byproducts. It is the best way to track geographic atrophy in advanced dry AMD, showing exactly where cells have been lost.

Ultrasound

When a dense cataract or vitreous hemorrhage blocks the view, B-scan ultrasound reveals whether the retina is attached behind the opacity. Painless, performed with gel on a closed eyelid.

Preparing for Imaging

Bring sunglasses and a driver in case of dilation, and bring prior images or reports from other offices — comparison is enormously valuable.

To schedule advanced retinal imaging, call (954) 633-8202.