[Preoperative Placido photography in keratoconus and its meaning in conjunction with postoperative astigmatism (author's transl)].

The preoperative shape of an eye affected by keratoconus can be evaluated by means of Placido photography of the cornea and the "Placido axis" of the main astigmatic error determined (Figs. 1, 2). In 64% of 105 cases it was shown that the postoperative astigmatism correlated well with the preoperative Placido axis (Table 5). A perfectly circular graft if transplanted, will therefore again adopt the preoperative shape of the cornea. From the facts above, a slightly oval graft sutured perpendicularly to the preoperative main Placido axis would probably compensate for this astigmatism but this has not been carried out experimentally as yet.