Purchase this article with an account.
D. A. Nelson, A. Ruf, D. Izhaky, Z. Burgansky-Eliash, H. Barash, A. Barak, A. Lowenstein, A. Grinvald; Retinal Capillary Map Imaged With No Contrast Agent Injection by the Retinal Function Imager. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1390.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Fluorescein Angiography (FA), widely used to document retinal vasculature, resolves capillaries and other fine vascular detail only transiently after contrast agent injection. The Retinal Function Imager (RFI, Optical Imaging, Ltd.) resolves the same structures by non-invasively imaging and enhancing intrinsic reflectance changes caused by continuously moving blood cells. We examined the level of microvascular detail a motion contrast image can provide.
Multiple RFI retinal image series (8 images, 55 Hz) were acquired from five healthy volunteers. After registration, pixel value distribution parameters in high spatial frequencies were analyzed to locate blood motion, thus tracing microvasculature in fine detail. For reference, optimal FA images from the same subjects were selected and contrast-enhanced.
The motion signal reveals microvascular detail, including surface capillaries, in as much and often greater detail than FA images (figure). The foveal avascular zone is sharply delineated in the RFI map shown. Available detail is focus-quality dependent, but images can be readily re-acquired. Multiple image series combination (4-10) is preferable; however, even one sharp series can produce a readable perfusion map. Left: Contrast enhanced FA image; Right: RFI perfusion map
The RFI's rapid sequential image series yield a motion signal that resolves even capillaries without the contrast agent and transient imaging time window associated with FA. This novel technique might serve as a non-invasive alternative to FA images for assessing perfusion abnormalities in patients with ischemic retinopathies.
This PDF is available to Subscribers Only