Based on the photographs, the Brow Position Index (BPI) was calculated for both the right (BPIR) and left (BPIL) sides. The BPI was defined as the ratio between the EN-EN (in pixels) and EX-EB (in pixels) distances multiplied by 100. Following, the difference (delta), in absolute value, between the preoperative BPI (BPI-pre) and 12month postoperative BPI (BPI-post) was calculated for both sides.