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Retinal Testing

Optical Coherence Tomography (OCT)

Optical coherence tomography (OCT) is a retinal scan used to study the anatomy of the retina in fine detail.

OCT testing requires dilation of the pupils but does not require a needle in the arm and does not involve touching the eye.  A healthy retina is only ¼ of a millimeter thick, but it contains multiple layers of specialized cells.

One layer converts light into nerve signals, another processes the nerve impulses, while another transmits these processed impulses to the brain where they are interpreted.

OCT testing is like having an optical biopsy of the retina; it provides excellent visualization of these layers of the retina, and aids greatly in the diagnosis and treatment of retinal disorders like AMD.

Not every patient needs an OCT test.  In some parts of Canada OCT testing performed for the evaluation of retinal disease is covered by provincial or territorial health plans.

Fluorescein Angiography

Fluorescein angiography, a clinical test to look at blood circulation inside the back of the eye, aids in the diagnosis of retinal conditions associated with diabetes, age-related macular degeneration, and other eye abnormalities.

The test can also help follow the course of a disease and monitor its treatment. It may be repeated on multiple occasions with no harm to the eye or body.

Fluorescein is an orange-red dye that is injected into a vein in the arm. The dye travels through the body to the blood vessels in the retina, the light-sensitive nerve layer at the back of the eye.

Fluorescein angiography is performed to evaluate the blood vessels in eyes with macular or retinal disease. A series of pictures of your macula and retina are then taken over approximately 15-20 minutes.

Most patients tolerate this test very well without any side effects. Some patients feel nauseated for a few minutes.

The technique uses regular photographic film, or, more commonly, is performed with digital equipment. No X-rays are involved.

If there are abnormal blood vessels, the dye leaks into the retina or stains the blood vessels. Damage to the lining of the retina or atypical new blood vessels may be revealed as well.

These abnormalities are determined by a careful interpretation of the photographs by your eye surgeon (ophthalmologist).

The dye can discolor skin and urine until it is removed from the body by the kidneys.

There is little risk in having fluorescein angiography, though some people may have mild allergic reactions to the dye. Severe allergic reactions have been reported but only very rarely.

Being allergic to X-ray dyes with iodine does not mean you will be allergic to fluorescein.

Occasionally, some of the dye leaks out of the vein at the injection site, causing a slight burning sensation that usually goes away quickly.

Information about eye conditions, disorders and treatments is presented courtesy of the Eye Physicians & Surgeons of Ontario.

Information about eye conditions, disorders and treatments is presented courtesy of the Eye Physicians & Surgeons of Ontario.