Practice the Basics: Hypofluorescence

Pattern #1: Blocked Fluorescence

Reduced visibility of underlying retinal or choroidal circulation due to a barrier located anterior to the circulation. The blocking material should become apparent when comparing the IVFA scan with a colour or red-free photo.

What are causes of blocked retinal fluorescence?

  • Vitreous material

  • Inner retinal material

Blocked Fluorescence Due to Vitreous Hemorrhage

Vitreous hemorrhage blocks the underlying retinal and choroidal fluorescence in all angiography phases.

What are causes of blocked choroidal fluorescence?

  • Subretinal Material

  • Deep Retinal Material

  • Material that blocks retinal fluorescence may also subsequently block choroidal fluorescence.

Pattern #2: Vascular Filling Defect

  • A filling defect causes darkness due to reduced perfusion - meaning less fluorescein is reaching the vasculature.

  • If there is a complete absence of perfusion, the hypofluorescence will persist throughout the whole angiogram. If there is only partially reduced perfusion, there will be delayed filling.

What causes a vascular filling defect in the retina?

  • Arterial Defect

  • Venous Defect

  • Capillary Bed Defect

  • Combination Defect

Now:

What causes a disc vascular filling defect?

  • Optic pit and coloboma

  • Vascular occlusion around the optic disc

  • Optic atrophy

Blocked Fluorescence Due to Subretinal Fluid

Notice that behind the area of hyperfluorescent neovascularization, the background fluorescence of the choroid is blocked and appears dark.

What causes a choroidal vascular filling defect?

  • Physiological

  • Posterior ciliary artery obstruction

  • Carotid obstruction

  • Absence of choroidal vascular tissue

Vascular Filling Defect from a Branch Retinal Artery Occlusion

Notice in the superotemporal area of the fundus, that there is darkness from hypoperfusion, and an artery that is not filled, despite all others demonstrating fluorescence.

Vascular Filling Defect from a Central Retinal Artery Occlusion

This frame of the IVFA occuring >30 seconds into the angiogram, shows poor perfusion of both the arterial and venous vasculature despite ample time passing for dye transit. Notice the lack of fluorescence of the venous system and partial fluorescence of particularly the arterial system.

Vascular Filling Defect; Nonperfusion from Capillary Dropout

While there are many features of hyperfluorescence in this photo related to proliferative diabetic retinopathy including neovascularization, notice the outlined blue areas of non-perfusion. Flow from major retinal arteries and associated capillaries is missing.

Practice the basics: Hyperfluoresence