Fluorescein Angiography
Confocal Laser Adds Detail and Dynamic Imaging
The transition from film to digital photography was primarily one of speed, helping to eliminate the waiting time for film developing and saving costs. The transition from flash photography to confocal laser imaging opens up a whole new world of diagnostic detail and perspective.
The first look at a laser image requires an adjustment. The initial impression can be that the image is “pixilated”, but as the observer looks through to the underlying image, new and greater detail begins to emerge.
Fluorescein angiography changes dramatically with confocal laser imaging due to two primary differences. The first difference is that the precise laser wavelength has been selected to generate the peak emission of light from fluorescein which increases the signal-to-noise-ratio. The second difference is the use of confocal imaging which blocks out-of-focus and scattered light, using the pinhole camera principle.
The results can be dramatic, revealing minute vessel detail in the fovea not visible in white flash photography. Since no flash is involved, the patient responds much better to follow up examinations.
The other advantage of using laser light is the high speed of image acquisition, allowing for dynamic imaging. So rather than watching a single “early” or “late” image, the clinician can watch the dye coursing through the vessels, appreciating narrowing and partial blockage not visible in static images.
With Spectralis® fluorescein angiography is not only dynamic, but can be combined with ICG angiography in a single injection, giving the clinician a view of both the retinal and choroidal blood flow. Alternatively the Spectralis® FA can be combined with simultaneous spectral-domain OCT, providing the exact location of the cross- sectional image.
