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Investigations
Special photographs are taken if your ophthalmologist is concerned about the possibility of wet macular degeneration. The photographs are called fluorescein angiograms (FA) and are done as an outpatient investigation. Photographs are obtained though a camera system, either with film or using digital technology. Pictures of the retina are taken as the dye is injected into a vein in the arm.
Picture #10 FA injection
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Within minutes of the injection, the dye reaches the eye and the procedure is usually over within 30 minutes. The test is very safe. The skin and urine will turn an orange yellow colour for approximately 24 hours, as the body clears the dye. A few patients have nausea or vomiting. Less than 5% of patients have an allergic reaction to the dye in the form of a rash or hives that usually occurs within minutes of the injection. If an allergic reaction occurs, antihistamine drugs may be given to reduce the reaction. In some rare instances, the allergy affects the windpipe, causing breathing problems. The FA allows the ophthalmologist to pinpoint the location of the blood vessel and guide the treatment.
Picture #11 FA normal
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Picture #12 FA CNVM
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If the blood vessel is difficult to find, the ophthalmologist may suggest another angiogram, but using a different dye. This dye, called indocyanine green (ICG), may give another view of the blood vessel. It is not as accurate as fluorescein, but it may be useful in some instances.
Picture #13 ICG
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High-speed video-angiography is a new technique that may improve the accuracy of locating the CNVM. Instead of still frame photography, high-speed video maybe able to capture the moments the vessels feeding the CNVM fill with dye.
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