What is Fluorescein?
Fluorescein is an ophthalmic dye and chemical substance that enhances the visualization of the eye’s tissues. The fluorescein stain has a yellow-orange tint. Eye doctors put fluorescein dye onto the eye in order to assess the health of the front of the eye (the cornea). The corneal integrity can be evaluated by looking at the features of the fluorescein eye stain. Fluorescein dye can also be injected into the arm, in a procedure called fluorescein angiography. The dye circulates through the blood vessels and to the eye, which allows for assessment of the health of the back of the eye (the retina).
- Fluorescein is an orange colored dye that can be put onto the cornea to assess the health of the front of the eye.
- Fluorescein angiography is a procedure where fluorescein dye is injected into the blood vessels of the arm in order to photograph the retina (back of the eye).
- Fluorescein angiography is useful for diagnosing and managing eye diseases such as diabetic retinopathy, retinal vascular disease, and macular degeneration.
Understanding Fluorescein Staining
Fluorescein is an organic, non-toxic, orange-yellow colored dye that is used to check the health of the eye. It is also called sodium fluorescein. Fluorescein can be put onto the front of the eye to assess the cornea, the clear covering that protects the front of the eye.
During the fluorescein staining test, the eye doctor will put fluorescein dye onto the front of the eye either by dabbing your eye with a thin strip of paper, or putting yellow-colored drops into your eye. When the fluorescein dye is put onto the front of the eye, it makes the tears appear yellow. You may notice that the tissue is yellow after you dab your eyes. The yellow appearance of fluorescein dye washes out within five minutes.
After placing fluorescein dye onto the surface of the eye, the eye doctor checks the health of the cornea. A blue-colored filter is used to view the yellow dye uptake. If the corneal cells are damaged, they will absorb the fluorescein dye and appear ‘stained’ bright yellow. Fluorescein staining refers to examining the fluorescence and dye absorption of the corneal cells. Cells will ‘stain’ yellow and are brightly fluorescent if they are dead or damaged.
Fluorescein staining can be used to diagnose several eye conditions, such as:
- Viral conjunctivitis
- Herpes simplex keratitis
- Herpes zoster keratitis
- Corneal abrasion
- Corneal ulcer
- Contact lens overwear
- Dry eye
Understanding Fluorescein Angiography
Fluorescein angiography is a procedure where fluorescein dye solution is injected into the arm. This procedure allows the eye doctor to assess the health of the retina, the back of the eye. The fluorescein dye circulates from the arm, through the blood vessels, and enters the blood vessels located in the back of the eye. Photograph images of the retina are taken immediately after the dye is injected into the arm and up to 10 minutes after. These photographs help the ophthalmologist see the blood vessels and other structures of the retina, as well as the pattern of blood flow in the retina. Fluorescein angiography is a helpful tool in identifying eye diseases.
Reasons To Get Fluorescein Angiography Performed
During fluorescein angiography, your retina is examined for improper blood flow. Your eye doctor might advise it for the following reasons:
- Macular Edema (Swelling)
This occurs when fluid accumulates in the macula, the part of the retina responsible for central vision. Macular swelling can happen due to poorly controlled hypertension, diabetes or macular degeneration. It may make the vision distorted.
- Diabetic Retinopathy
Poorly controlled diabetes can result in vision loss or blindness due to bleeding in the retina. As diabetes damages the retina, there is less oxygen going to the cells and the blood vessels in the retina can leak. Diabetes is the leading preventable cause of blindness in the United States.
- Macular Degeneration
Macular degeneration is a disease caused by a buildup of waste products in the retina and can result in loss of central vision. A less common type of macular degeneration, wet age-related macular degeneration, can cause bleeding in the retina. This bleeding can be identified with a fluorescein angiogram.
- Retinal Vascular Occlusion
Retinal vein occlusion is a blockage of the veins that carry blood out of the retina. It can lead to severe vision loss and bleeding. Retinal artery occlusion, a lack of supply of blood into the retina, causes retinal tissue death and is associated with stroke. Fluorescein angiography can detect blockage of the retinal veins and arteries.
Risks Associated With Fluorescein Angiography
Fluorescein angiography is a minimally invasive procedure that involves inserting a needle into the arm to inject the fluorescein dye solution. No incisions, cuts, or surgery is performed during this procedure. As with any minimally invasive procedure, fluorescein angiography has risks. However, the risks of fluorescein angiography are low and it is generally a well-tolerated procedure that is routinely performed without complications.
The most common side effect of fluorescein angiography is nausea. Approximately 10% of patients who undergo the procedure will feel mild nausea during the procedure. Other less common side effects of fluorescein dye injection are vomiting, itchy skin or rash at the site of the injection , and fainting. The most serious complication of fluorescein angiography is anaphylaxis, which is a life-threatening allergic reaction that can result in death. Anaphylaxis is a very rare occurrence and only happens to approximately 1 in every 200,000 patients. Facilities that perform fluorescein angiography are always equipped to manage complications that may occur.
After being injected into the arm, the orange fluorescein dye is eliminated by the liver and kidneys within 24 hours. Because the dye is eliminated from the body through the urine, the urine will appear orange for up to 24 hours after the fluorescein angiography procedure is completed.