Hypofluorescence can occur secondary to aīlockage of normal fluorescence may result when any opacity occurs anterior to the fluorescence. Hypofluorescence is a reduction from the normal expected fluorescence and hyperfluorescence refers to an increased or abnormal fluorescence. Abnormal Fluorescein Angiographyĭeviations from the normal FA are most often described in terms of relative fluorescence. After 10 minutes fluorescein is usually no longer seen in retinal vessels however several structures including the optic nerve head, Bruch’s membrane, and sclera are stained with fluorescein and continue to fluoresce. The recirculation phase occurs approximately 3-5 minutes after injection of fluorescein. The peak phase with maximal fluorescence occurs at approximately 30 seconds and recirculation phases follow. In the normal macula, the capillary-free zone is seen as dark due to blockage of choroidal fluorescence by xanthophyll pigment and tightly packed retinal pigment epithelial cells. This is followed by the late arteriovenous phase or laminar venous phase as the dye fills the veins in a laminar pattern. The early arteriovenous phase describes the filling of the retinal arteries, arterioles and capillaries. The retinal circulation appears 1-3 seconds later (11-18 seconds after injection). The filling of the choroidal circulation is seen as the choroidal flush, a patchy and mottled hyperfluorescence as the choroidal lobules fill. This is dependent on the age and cardiovascular status of the patient as well as the speed of dye injection. Further, imaging facilities should be adequately equipped and prepared to manage complications associated with fluorescein angiography.įollowing injection into an antecubital vein, dye passes through the short posterior ciliary arteries and appears in the optic nerve and choroid usually within 8-12 seconds. Despite the relatively low rates of serious adverse events, informed consent should always be obtained prior to performing fluorescein angiography. No serious adverse events have been reported to occur in pregnancy however it is considered a contraindication. Death is estimated to occur in 1:221,781. Severe life-threatening reactions such as anaphylaxis, cardiac arrest, and bronchospasm do occur but are extremely rare. Local tissue necrosis can occur with extravasation of dye, however, mild pain and redness is more typical. More severe reactions such as urticaria, pyrexia, thrombophlebitis, and syncope are more rare. The most common reactions are transient nausea that occurs in 3-15% of patients, vomiting (7%), and pruritus. The images are recorded digitally or on 35mm film.Ī wide range of complications can occur with FA. Images are acquired immediately after injection and continued for ten minutes depending on the pathology being imaged. A barrier filter of 520-530nm allows capturing only light emitted from the excited fluorescein. Blue light (wavelength 465-490 nm) is then absorbed by unbound fluorescein molecules, and the molecules fluoresce, emitting light with a longer wavelength in the yellow-green spectrum (520-530nm). White light from a flash is passed through a blue excitation filter. Fluorescein dye is injected intravenously, usually through an antecubital vein with sufficient speed to produce high contrast images of the early phases of the angiogram. More modern advances such as digital imaging and computer software analysis have further enhanced the utility of the procedure.įA requires the use of a dedicated fundus camera equipped with excitation and barrier filters. John Donald McIntyre Gass began publishing his experience with FA in 1967 and his efforts led to the wider acceptance of the technique in the evaluation of retinal disease. Alvis, described and demonstrated the technique of retinal fluorescein angiography (FA) in 1961. It does not store any personal data.Two medical students from Indiana University, Harold R. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly.
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