How does focal hyperpigmentation typically appear on fundus autofluorescence (FAF)?

Focal hyperpigmentation on fundus autofluorescence (FAF) typically appears as areas that may hyperautofluoresce. This occurs because hyperpigmented regions often indicate an accumulation of lipofuscin, which contributes to increased autofluorescence signal. The elevated levels of lipofuscin in these regions lead to a brighter appearance on FAF imaging. This is important for clinicians as it can help in the diagnosis and monitoring of various retinal conditions, particularly those involving changes related to age-related macular degeneration (AMD).

In contrast, other options relate to different types of FAF appearances. Areas that hypoautofluoresce would indicate a loss of signal, usually due to the absence of lipofuscin or retinal pigment epithelium (RPE) dysfunction. Dark areas could indicate atrophic changes or lesions where autofluorescence is not present, and stating that it is not visible on FAF would suggest an absence of any detectable change, which is not applicable to focal hyperpigmentation.