Optical Coherence Tomography (OCT)
Angiography is an important diagnostic test in which detailed photographs of the retina and choroid are taken after injecting a dye into an arm vein. The test is performed in the office and involves sitting in front of a special camera while flash photographs are taken. Initially, the dye is painlessly injected into an arm vein and then travels up into the eyes. When the dye arrives in the eye circulation, the photographs begin. The test usually lasts from 10 to 30 minutes. No X-rays are taken. Patients who are allergic to x-ray dye are not necessarily allergic to sodium fluorescein.
Two different dyes are available for injection into the vein: fluorescein or indocyanine green. Fluorescein dye is removed from the body by the kidneys and ICG dye by the liver. After fluorescein angiography, the urine and skin turn orange for up to 24 hours, after ICG angiography, no color changes in the urine or skin are noticed. Fluorescein angiography is the best test to view the retinal circulation while ICG angiography is better to view the choroidal (layer under the retina) circulation.
Fluorescein angiography is the most common test performed by the vitreo-retinal specialist. It is useful for diagnosing retinal or optic nerve conditions, guiding laser surgery, and following the course of your condition. Diabetic retinopathy, macular degeneration, retinal vein occlusions, and macular edema are just some of the more common disorders that fluorescein angiography is helpful in assessing.
Abnormal Fluorescein Angiogram Image Normal Fluorescein Angiogram Image
ICG
angiography is most helpful in patients with "wet" macular degeneration.
Abnormal blood vessels that grow underneath the retina are sometimes blocked by
blood or pigment when imaged with fluorescein. These same blood vessels may be
visible with ICG. If they are precisely located, laser surgery may be offered.
ICG is also useful in evaluating ocular tumors and inflammatory conditions.
Side effects of the procedure include nausea and a yellow staining of the skin
at the site of the injection. Nausea, when it occurs, usually passes within a
few seconds. Staining of the skin may occur if the fluorescein dye leaks out of
a fragile vein, and may also be accompanied by localized burning. The burning
usually lasts only a few minutes, and the staining will go away after a few
days. Allergic reactions to fluorescein dye are uncommon. If allergies do occur,
they may manifest as a skin rash or itching. Depending on the severity of the
allergic reaction, the treatment may take the form of an oral or injectable
antihistamine. Rarer still, are severe allergic reactions or anaphylaxis, which,
if they do occur have the potential to be life threatening.
ICG dye contains iodine. Severe allergic reactions may occur when ICG is
injected into those people who are allergic to iodine. If you suspect that you
are allergic to substances that contain iodine, including X-ray dyes and
shellfish, you must alert you physician.
OCT uses a scanning light beam to acquire a high resolution cross section of the retina. This test is done in the office, and simply requires the patient to sit in front of a special camera. Since only light waves are used, no radiation is involved with this test. The information gathered by this test allows for accurate and reproducible images of the retina to be generated. It has been found to be particularly useful in the analysis of retinal conditions such as macular degeneration, macular edema, macular holes, macular puckers, diabetic retinopathy, and vein occlusions.
NORMAL OCT ABNORMAL OCT
Ultrasound uses sound waves to help visualize the back of the eye. It is just like the ultrasound that is used to look at the fetus during pregnancy, but obviously the ultrasound instrument for the eye is much smaller. Ultrasound is a painless quick way of obtaining a clear view of the retina when either swelling, cataract, or blood in the front of the eye is obscuring the physician’s view to the back of the eye.
