Fundus autofluorescence (FAF)

Fundus spectrophotometric studies in vivo by Delori and co-workers, have shown that FAF represents an accumulation of lipofuscin in the lysossomes of RPE cells, mainly derived from photoreceptors outer segments degradation.

The compound is found as micrometer-sized spherical particles and is characterized by yellow autofluorescence when exposed to blue light^(42,43,44).

It has been shown with confocal scanning laser ophthalmoscopy (cSLO) that FAF response is very low or extinguished in areas of atrophy.

The lack of RPE cells or its low number and therefore of lipofuscin, (the dominant fluorophore) explain this reduction⁽⁴⁵⁾.

Increased FAF precedes development of GA^(46,47).

FAF is increased in junctional zone around areas of atrophy, and intensity seems to correlate with extension of the atrophic area, and also with reduction of retinal sensitivity detected by fundus perimetry^(48,49).

Despite the works of Holz and Valkenberg, the prognostic value of FAF remains controverse.

In a recent study, FAF was not a strong risk factor for development or extension of GA⁽⁵⁰⁾.