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 vasculature called chorioretinal optical sectioning (CROS). CROS consists of projecting a laser beam at an angle on the retina after injection of a fluorescent dye and viewing the fluorescence. On the fluorescence optical section (FOS) image, the vasculature of the retina and choroid appear laterally displaced 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 microm on the retina. Optical section images of the vascular layers are constructed from the series of FOS images. RESULTS CROS permitted optical separation of vascular layers in living eyes. Optical section images of normal and laser-photocoagulated retinas had higher contrast than conventional angiography because of the separation of the fluorescence from the overlapping layers and allowed enhanced visualization of vascular abnormalities. CONCLUSIONS CROS enhances the visualization of the retinal and subretinal vasculature and promises to be a beneficial tool for evaluation of chorioretinal diseases.