ABSTRACT
Different techniques are used for acquiring retinal images. Most common are colored or monochromatic photography and angiography using fluorescent dyes. In monochromatic photography, color filters are used to select light wavelengths that enhance the visibility of various fundus structures. Lighting using wavelengths close to the green region of the spectrum (known as red-free lighting) is frequently employed, as it leaves vessels, hemorrhages, and exudates more apparent. Angiographies, on the other hand, require the injection of a small amount of fluorescent dye
Detection of
into the patient, usually sodium fluorescein or indocyanine green. Fluorescence angiography permits recording of blood vessels and flow and also the detection of eventual leakages, of interest for diagnostic purposes. However, it is inadequate for screening programs, as angiograms can only be obtained by specialists in ophthalmology clinics, and is invasive, presenting a certain risk of side effects to the patient.
