Clinical use and research applications of Heidelberg retinal angiography and spectral-domain optical coherence tomography - a review

Fluorescein angiography (FA) was discovered by Nowotny and Alvis in the 1960s of the 20th century and has evolved to become the 'Gold standard' for macular diagnostics. Scanning laser imaging technology achieved enhancement of contrast and resolution. The combined Heidelberg retina angiograph (HRA2) adds novel innovative features to established fundus cameras. The principle of confocal scanning laser imaging provides a high resolution of retinal and choroidal vasculature with low light exposure providing comfort and safety for the patient. Enhanced contrast, details and image sharpness image are generated using confocality. For the visualization of the choroid an indocyanine green angiography (ICGA) is the most suitable application. The main indications for ICGA are age-related macular degeneration, choroidal polypoidal vasculopathy and choroidal haemangiomas. Simultaneous digital FA and ICGA images with three-dimensional resolution offer improved diagnosis of retinal and choroidal pathologies. High-speed ICGA dynamic imaging can identify feeder vessels and retinal choroidal anastomoses, ensuring safer treatment of choroidal neovascularization. Autofluorescence imaging and fundus reflectance imaging with blue and infrared light offer new follow-up parameters for retinal diseases. Finally, the real-time optical coherence tomography provides a new level of accuracy for assessment of the angiographic and morphological correlation. The combination of various macular diagnostic tools, such as infrared, blue reflectance, fundus autofluorescence, FA, ICGA and also spectral domain optical coherence tomography, lead to a better understanding and improved knowledge of macular diseases.