Fluorescein angiography Fluorescein angiography , or fluorescent angiography , is a technique for examining the circulation of the retina . It involves injection of sodium fluorescein into the systemic circulation , and then an angiogram is obtained by photographing the fluorescence emitted after illumination of the retina with blue light at a wavelength of 490 nanometers . The fluorescein dye also reappears 12-24 hours in the patient urine , causing a yellow-green appearance . Some patients have an allergic reaction to the dye . Most commonly ( 1 out ten patients ) have an outbreak of itchy hives , however rarely patients may enter anaphylactic shock . Equipment Exciter filter : allows only blue light to illuminate the retina . It reduces the amount of non-fluorescent light that can reach the film , and allows for maximum excitation of the fluorescein . Barrier filter : allows only yellow-green light ( from the fluorescence ) to reach the camera . It absorbs the blue light used to illuminate the retina . Camera with black and white film . Also digital cameras have come into use since the late 1990's . Technique Baseline color and red-free filtered images are taken prior to injection . This allows for the recognition of autofluorescence of the retinal tissues . Injection of approximately 5cc of sodium fluorescein into a vein in the arm or hand . A series of black-and-white or digital photographs are taken of the retina after the fluorescein reaches the retinal circulation ( approximately 10 seconds after injection ) . Photos are taken approximately once every second for about 20 seconds , then less often . A delayed image is obtained at 5 and 10 minutes . Some doctors like to see a 15 minute image as well . A filter is placed in the camera so only the fluorescent , yellow-green light ( 530 nm ) is recorded . The camera may however pick up signals from pseudofluorescence or autofluorescence . In pseudofluorescence , non-fluorescent light is imaged . This occurs when blue light reflected from the retina passes through the filter . This is generally a problem with older filters , and annual replacement of these filters is recommended . In autofluorescence , fluorescence from the eye occurs without injection of the dye . This may be seen with optic nerve head drusen , astrocytic hamartoma , or calcific scarring . Black-and-white photos give better contrast than color photos , which are n't necessary since only one color is being transmitted though the filter . Normal circulatory filling times are approximate 0 seconds — injection of fluorescein 9.5 sec — posterior ciliary arteries 10 sec — choroidal flush ( or `` pre-arterial phase '' ) 10-12 sec — retinal arterial stage 13 sec — capillary transition stage 14-15 sec — early venous stage ( or `` lamellar stage '' , `` arterial-venous stage '' ) 16-17 sec — venous stage 18-20 sec — late venous stage 5 minutes — late staining Fluorescein enters the ocular circulation from the internal carotid artery via the ophthalmic artery . The ophthalmic artery supplies the choroid via the short posterior ciliary arteries and the retina via the central retinal artery , however , the route to the choroid is typically less circuitous than the route to the retina . This accounts for the short delay between the `` choroidal flush '' and retinal filling . Pathologic findings Pathologic changes are recognized by the detection of either hyperfluorescence or hypofluroescence . Causes of hyperfluorescence : leaking ( i.e. capillary leakage , aneurysm , neovascularization ) pooling ( serous retinal detachment ) staining transmission defects abnormal vessels Causes of hypofluorescence : optical barrier ( i.e. blood ) filling defect ( capillary blockage ) Among the common groups of ophthalmologic disease , fluorescein angiography can detect diabetic retinopathy , vein occlusions , retinal artery occlusions , edema of the optic disc , and tumors . Other types of fluorescent angiography Indocyanine Green Angiography References Angiography images See also Fundus camera Categories : Ophthalmology 