A method of processing optical coherence tomography (OCT) scans of a subjects skin (7), the skin (7) having a surface (8), the method comprising capturing a plurality of scans through the subjects skin (7), the scans representing an OCT signal in slices through the users 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.
