Fundus autofluorescence (FAF) imaging uses the intrinsic fluorophore of the RPE. Which molecule is primarily responsible for the autofluorescence signal in a normal eye?

• A Melanin
• B Xanthophyll pigment
• C Rhodopsin
• D Lipofuscin (A2E and bisretinoids) ✓

Explanation

Lipofuscin, accumulated in RPE lysosomes as a byproduct of outer segment phagocytosis, is the primary source of fundus autofluorescence. The major fluorophore is A2E (N-retinylidene-N-retinylethanolamine) and related bisretinoids. Excess lipofuscin causes hyperfluorescence (as in early AMD or Stargardt's), while RPE atrophy causes hypofluorescence due to absence of RPE cells. Melanin actually absorbs and quenches autofluorescence.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.