Photographs illustrate different surgical techniques used to induce scar formation. A horizontal cut, technique 1 (A), horizontal abrasion into the stroma, technique 2 (B), and central cut and abrasion on both sides, technique 3 (C). Dash lines symbolize abrasion to the stroma with an AlgerBrush II burr. Arrowheads show keratotomy. Scar formation in the three surgical injury models studied. Different examples of scar tissue obtained by a horizontal cut into the stroma, technique 1 (D and G), horizontal abrasion technique 2 (E and H), and central cut and abrasion on both sides, technique 3 (F and I).