A method of processing optical coherence tomography (OCT) scans of a subject s skin (7) the skin (7) having a surface(8) the method comprising capturing a plurality of scans through the subject s skin(7) the scans representing an OCT signal in slices through the user s skin (7) in parallel planes the scans being offset from one another along a direction perpendicular to the parallel planes the method comprising determining the position of the surface (8) of the skin (7) in each scan and displaying the scans to a user with an indication (9) indicative of a predetermined depth below the surface (8) of the skin (7) visible to the user.
