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Applications of the Sodium Fluorescein technique
The most common example of this technique is angiography of the retina where fluorescein is injected into the patient's vein in the antecubital fossa, and the dye's journey into the retinal vessels recorded with a special retinal camera. Figure 46 shows the type of result obtained. This technique is invaluable in the assessment of many conditions, including diabetes, and is often considered one of the truly diagnostic uses of photography. Fluorescein angiography is a separate subject in its own right, and the interested reader is referred to the excellent series by Wong (1976, 1977) for practical details.
The fluorescein technique is also useful for other types of patient photography. Injecting the dye and then photographing its resultant distribution pattern may be useful in studies of blood flow to tumours, reconstructive flaps, grafts, etc., where surgeons often require an "immediate" result in the operating room. Figure 47, Figure 48, Figure 49 and Figure 50 are all examples of the use of the technique to outline the blood flow. In what has become a classic example of fluorescein mapping in surgery Feindel, Yamamoto and Hodge (1967) demonstrated that they could distinguish between different types of blood vessel in complex neurological tumours, greatly facilitating speedy and efficacious surgery (Figure 51). Hodge's work is often regarded as the definitive work on the sodium fluoresence technique (Hodge 1978).
Sodium fluorescein is also used in ophthalmology for the assessment of corneal ulceration (Figure 52) and for the assessment of the fit of contact lenses (Figure 53). In the case of an ill-fitting contact lens, the fluorescein "pools" underneath the lens where there is not a good fit. In both instances, the sodium fluorescein is placed onto the anterior surface of the eye as drops. In the case of corneal ulceration, the ulcerated area absorbs the dye, whereas the dye is washed from the intact conjunctiva by the tears. Only the ulcerated area, therefore fluoresces and this is extremely useful in assessing what is essentially a transparent change on a transparent medium (Figure 54).
Some of the more important reported applications of the sodium fluorescein technique are listed in tabular form below:
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Last modified: 3 May 2002