What is oral fluorescein angiography?
Fluorescein angiography (FA) is a useful method of photographing the eye. Although it is usually used to study the blood flow to the retina, it is also used to study the iris and other eye structures. FA is usually performed by injecting fluorescein dye into a vein of the arm, after which special photographs are taken of the eye. However, when a vein is not easily accessible, the dye may be administered by mouth in the form of a drink.
When to consider oral fluorescein angiography?
Oral fluorescein angiography may be considered whenever access to a vein presents a challenge. Sometimes, this situation is encountered with children or adults who are strongly averse to pain, as the dye injection may be uncomfortable. In other cases, the veins are simply too small or are otherwise difficult to inject. In these instances, oral fluorescein angiography may be considered as an alternative to intravenous FA.
What is the disadvantage of oral fluorescein angiography?
The main disadvantage of oral FA is a potential decrease in the quality of the images of the retina. However, there are several steps that may be taken to optimize the image quality. Another disadvantage of oral FA is that the dye tastes bitter. The may be overcome, in part, by mixing the fluorescein dye with apple juice or with water sweetened by sugar or a non-nutritive sweetener.
How is the procedure performed?
For adults, two 5ml vials containing fluorescein 10% solution are mixed in a cup with 1-4 ounces of apple juice, orange juice, or sweetened water. The best images are achieved if the drink is consumed in one gulp. It is fine to “wash down” the bitter taste with additional beverage of choice. Using an SLO fundus camera programmed for FA, take one photo per minute for each eye (set timer) until the retinal vessels start to fill. This is usually about 4-5 minutes from start time. Once all the vessels fill well, peripheral views may be captured. Afterwards, one image is captured every 5 minutes until ending the photos 20-30 minutes from the start time. If the images are not satisfactory, the test may be repeated after an overnight fasting without food.
How is the fluorescein dosage adjusted by patient weight?
The amount of 10% fluorescein dye may be adjusted downward for patients weighing less than 90 pounds. This adjustment is especially important for children. The recommended dosage is 25mg/kg. As fluorescein dye is supplied in 5ml vials of 10% solution for injection, the table below may be used for dosing by weight in pounds:
| Patient Weight (lbs) | Fluorescein 10% Dose |
| 40 | 4.5cc |
| 50 | 5.5cc |
| 60 | 6.5cc |
| 70 | 8.0cc |
| 80 | 9.0cc |
| 90 | 10cc |
| >90 | 10cc |
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