A TikTok trend is advising women use sunscreen to contour areas of their face Recommends using a higher factor under your eyes and on your cheek bones Trend began when Eli Withrow, 24, an LA model, went viral with the tip last year Now thousands of others are trying out the trend to add shape to their cheeks Celebrity make up artist Sir John Barnett once recommended performing hack Experts have said the trend is 'dangerous' and could cause 'significant damage'