L’imagerie du fond d’oeil en auto-fluorescence (FAF) est un procédé d’imagerie in vivo reflétant la distribution naturelle ou pathologique de fluorophores au niveau du fond d’oeil. Ainsi, cette technique d’imagerie fournit des informations sur l’état de l’épithélium pigmentaire rétinien (EPR).
Bien que la rétine contienne de nombreux fluorophores, la fluorescence provient principalement de la lipofuscine qui est un pigment oculaire issu du métabolisme intracellulaire dans les photorécepteurs et l’EPR. La présence de lipofuscine en excès accentue l’auto-fluorescence et inversement.
63 year old male with an end-stage CNV scar tissue in the macula, visual acuity is 10/200. The scar tissue is well demarcated on the color fundus image, however, the FAF image shows the real extent of the pathology reaching out almost until the vascular arcades. The patchy hyperfluorescence around the scar indicates some remaining functional RPE.
A 39 year old female with mild visual symptoms in her left eye and a visual acuity of 20/20. Note the white spots around the macula which are showing hypofluorescence on FAF with minimal surrounding hyperfluorescent areas in some of the lesions. There are much more lesions visible on FAF compared to the color image. There was no activity seen neither on FLA nor with OCT.
35 year-old female with advanced Stargardt’s disease, visual acuity is 1mcf. The FAF image shows the excessive loss of RPE cells in the macula, which is correlated with the color fundus image. The surrounding patchy hypofluorescence is indicative of rod photoreceptor loss which is not evident on the color fundus image.
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FAF takes advantage of the fluorescent properties of lipofuscin, a normal by-product of photoreceptor metabolism. With age, lipofuscin accumulates in many types of cells throughout the body. In the eye, the retinal pigment epithelium (RPE) is particularly susceptible. Excessive build-up of lipofuscin in the RPE interferes with normal cell function, leading to photoreceptor degeneration and even cell death.
Rune Brautaset BSc (Hon), MPhil, PhD, Associated professor, and Head of Unit/Director of Studies, Unit of Optometry/Optometry Education, Karolinska Institutet, St Erik's Eye Hospital, Stockholm, Sweden