Diagnostic Retinal Testing

Fluorescein Angiography

Fluorescein Angiography is a diagnostic test that uses a special camera to take pictures of the back of your eye. This enables your ophthalmologist to thoroughly diagnose and monitor certain retinal diseases and abnormalities, which may otherwise go undetected without the use of fluorescein angiography. This test may be performed the day of your visit, or scheduled for you to come back another day.

A teaspoon of water-soluble dye, called sodium fluorescein, is injected into a vein of your arm or hand. As the dye circulates throughout your body, the retinal photographer will take multiple pictures of the retinal blood vessels as the dye passes through them. After the fluorescein dye is injected, your skin may look faintly yellow for several hours. This does not mean jaundice or hepatitis. As the dye passes through your kidneys, your urine will turn dark orange or yellow over the next twenty-four hours.

A small percentage of individuals may experience nausea or vomiting after the injection of dye. However, this is transient, and usually passes within a minute or two. If some of the dye leaks out from the vein and into your arm under the skin, you may feel a localized burning sensation that lasts only a few minutes. Allergic reactions to fluorescein dye are rare. If they occur, they may cause a skin rash or itching. This is usually treated with oral or injectable antihistamines, depending on the severity of the symptoms. Even more rarely, severe allergic reactions can occur that are life threatening. Please inform your doctor if you are pregnant, had breast surgery or have had an adverse reaction in the past.

After the photos are taken, your doctor will discuss with you what follow up is needed. A treatment plan will be formulated for you by your ophthalmologist after careful examination and interpretation of your angiogram.

Optical Coherence Tomography

OCT is a new, non-invasive technology used for imaging the retina, the multi-layered sensory tissue lining the back of the eye. OCT, the first instrument to allow doctors to see cross-sectional images of the retina, is revolutionizing the early detection and treatment of eye conditions such as macular holes, pre-retinal membranes, macular swelling and even optic nerve damage.

Similar to retinal CT scans of internal organs, OCT uses the optical backscattering of light to rapidly scan the eye and describe a pixel representation of the anatomic layers within the retina. Each of these ten important layers can be differentiated and their thickness can be measured. A retinal ophthalmologist, knowing the normal thickness of a healthy retinal layer, can then distinguish a multitude of retinal diseases and conditions.

For certain conditions, such as age-related macular degeneration and cystoid macular edema, the 45 second OCT procedure is able to reduce or eliminate the need for fluorescein angiography for some patients.

Normal OCT. The retina has ten layers and should show a “dip” in the middle of the retina. Clinically this is the macula and is the area responsible for central vision.

Atrophic (Dry) Macular Degeneration

Dry macular degeneration appears realtively normal on OCT testing. Drusen can be seen as subretinal deposits, and geographic atrophy can be seen as retinal thinning.

Exudative (Wet) Macular Degeneration

Wet macular degeneration is characterized by subretinal tissue and fluid on OCT testing. The complex of vessels can be seen as a subretinal mass with associated subretinal and intraretinal fluid. Response to treaments can also be followed. Successful treatment can show resolution or reduction in fluid.