This lavishly illustrated unique atlas provides a comprehensive and up-to-date overview of FAF imaging in retinal diseases. It also compares FAF findings with other imaging techniques such as fundus photograph, fluorescein- and ICG angiography as well as optical coherence tomography. General ophthalmologists as well as retina specialists will find this a very useful guide which illustrates typical FAF characteristics of various retinal diseases.
It has been known for many years from histopathological studies that autofluorescence
is present in the retinal pigment epithelium (RPE) due to the presence of lipofuscin.
The demonstration that the excitation spectrum of the “orange-red” fluorophores
extends into the visible range indicated that imaging of lipofuscin was accessible to
in vivo excitation. However, in vivo recording in humans of autofluorescence using
spectrophotometric techniques and imaging with a scanning laser ophthalmoscope
are relatively recent.
It is believed that the level of autofluorescence represents a balance between accumulation
and clearance of lipofuscin. Accumulation of fluorescent material in the
RPE reflects the level of metabolic activity, which is largely determined by the quantity
of photoreceptor outer segment renewal. Abnormally high levels are thought
to be due to RPE cell dysfunction or to the RPE’s being subjected to an abnormal
metabolic load as occurs in Stargardt disease, in which the discs contain abnormally
high levels of N-retinylidene-N-retinylethanolamine (A2-E). Evidence of clearance
is derived from the observation that outer retinal degeneration is associated with decreased
autofluorescence.
This could be due to a variety of factors. There appears to be
constant degradation of residual bodies in the RPE. There is evidence of photodegradation
of A2-E, and in addition, long-term phagolysosomes may be discharged from
the RPE cells into the extracellular space.
