Which test makes CHRPE more visible?

• A. Fundus photo
• B. Red-free photo
• C. FAF
• D. OCT

Answer: (B)

The key idea is that surface contrast for pigmented retinal lesions is highest when you use illumination that enhances pigment differences against the surrounding tissue. A red-free (green) filter does just that: it transmits green light that increases contrast between the pigmented RPE cells of CHRPE and the adjacent retina, making the lesion appear as a sharp, well‑defined dark patch. This makes CHRPE stand out more clearly than in a standard color fundus photo, autofluorescence imaging, or OCT, where the pigment and surface edges aren’t emphasized as effectively. Autofluorescence can show hypoautofluorescence in CHRPE due to reduced lipofuscin, and OCT provides cross-sectional architecture rather than surface contrast, so they don’t highlight the lesion as clearly as red-free imaging.