A new method for noninvasive optical sectioning of the chorioretinal vasculature

PURPOSE. To report a new method for optical sectioning of the chorioretinal vasculature to improve the visualization of vascular abnormalities due to chorioretinal eye diseases. METHODS. An imaging system was developed for optical sectioning of the vasc ulature called chorioretinal optical sectioning (CROS). CROS consists of pr ojecting a laser beam at an angle on the retina after injection of a fluore scent dye and viewing the fluorescence. On the fluorescence optical section (FOS) image, the vasculature of the retina and choroid appear laterally di splaced according to their depth location. The laser beam is scanned over a 2 X 2-mm area to generate 40 FOS images, each spatially separated by 50 mu m on the retina. Optical section images of the vascular layers are constru cted from the series of FOS images. RESULTS. CROS permitted optical separation of vascular layers in living eye s. Optical section images of normal and laser-photocoagulated retinas had h igher contrast than conventional angiography because of the separation of t he fluorescence from the overlapping layers and allowed enhanced visualizat ion of vascular abnormalities. CONCLUSIONS. CROS enhances the visualization of the retinal and subretinal vasculature and promises to be a beneficial tool for evaluation of choriore tinal diseases.