Confocal Indocyaningreen-angiography with threedimensional topography: First clinical results
U. Schmidt-Erfurth1, J. Noack2, R. Birngruber2
Purpose: Confocal Indocyaningreen-Angiography (ICG-A) offers a detailed imaging of choroidal pathologies in a two-dimensional mode. However, the extension of proliferative processes into adjacent layers, mainly retinal structures, as well as the depth of vascular defects located within the choroid are not accessible for evaluation. We developed a novel method for a three-dimensional documentation of retinal and most importantly choroidal vascular structures. First clinical results are being presented.
Method: Focal series using a confocal laser scanning ophthalmoscope (Heidelberg Retina Angiograph) were performed within 1-2 minutes after dye administration. 32 images within a section of 4 mm were taken at a frequency of 20 Hz. Following correction for lateral and rotational movements, layers of normalized isointensity fluorescence were determined.
Results: The physiological choroid demonstrates a homogenous concave surface with a lobuled pattern. Cover effects due to blood or pigment are completely eliminated by the method. Classic choroidal neovascularization (CNV) is characterized by a lesion showing an elevated border with central depression. Occult CNV also present as prominent lesions with smooth, convexe borders. Progression of CNV over 12 months is documented by increasing spread in lateral direction. Therapeutic interventions such as ALK, PDT or surgery induce a regression in height back to the level of physiological choroid with or without residual defect within the choroidal pattern. A loss of the capillary layer as found with macular dystrophies is seen as well-demarcated depression of the choroidal surface. Choroidal infiltrates also appear as localized choroidal defects. Laser effects induce choroidal wholes only months after application.
Conclusion: Confocal Laser Angioscopic Topography (CLAST) allows for the first time an in vivo-imaging of height and depth of vascularized lesions. A novel characterization of pathologic proliferation e.g. CNV as well as perfusion defects, a precise follow-up after therapy and monitoring of dynamic exudative processes using consecutive series become available.
1 University Eye Clinic Lübeck, Ratzeburger Allee 160, D-23538 Lübeck
2 Medical Laser Center Lübeck, Peter-Monnik-Weg 4, D-23562 Lübeck