Heuermann,[10] in 1756, had already antedated these thoughts of Sharpe by practising a similar method. He passed a double edged lance-knife through the cornea instead of through the sclera, and then made a sweeping incision through the iris-membrane without enlarging the corneal wound. He was probably the first to puncture the cornea with the iris-knife. [10] Heuermann, Georg: Abhandlung der Vornemsten Chirurgischen Operationen, Copenhagen and Leipzig, 1756, ii, p. 493. Janin,[11] about 1766, performed Cheselden’s operation several times with but little success owing to reclosure of the wound by plastic exudate. He adopted Sharpe’s modification, but later on changed the incision from a horizontal to a vertical one with better results. He, however, afterward abandoned this procedure and became the originator of the other school, composed of those who preferred to use the scissors. [11] Janin, Jean: Mémoires et Observations sur L’Oeil, Lyon 1772, p. 191. Guérin,[12] in 1769, made a free corneal incision with a large cataract knife, and then introduced a small iris-knife, with which he made a crucial incision from before backward in the center of the iris-membrane. Although Guthrie[6] distinctly states that Guérin afterwards removed the four angles of the cross with a pair of scissors in order to prevent reclosure of the incision, no direct confirmation of this statement can be found in his writings. [12] Guérin, M.: Maladies des Yeux, Lyon 1769, p. 235. Beer,[13] in 1792, first published his method, which he designated as “an improvement on Cheselden’s method.” Although the technic is somewhat different, the procedure is practically the same as that originated by Heuermann in 1756. Beer selected certain cases in which a prolapsed iris had followed the lower incision for cataract, causing adherent leucoma with a tensely drawn iris-membrane. He plunged his double-edged lance-knife (Fig. 5) through the cornea and stretched out iris, from above downward and a little obliquely (Fig. 6), so as to incise the center of the tense iris fibers crosswise, at right angles to the line of traction; cutting horizontally when the traction was vertical, and vertically when this was horizontal. In his monograph on artificial pupil,[14] 1805, he substitutes for the lance-knife his new broad iris-knife, which is practically the same as that later shown by Walton (vide Fig. 12), as, indeed, Walton’s procedure (vide Fig. 13) was almost identical with that of Beer. For other conditions he usually employed Wenzel’s operation until by chance he encountered a puzzling case which led him to perform the operation we now know as iridectomy (1797) and which thereafter became his favorite procedure for artificial pupil. [13] Beer, Georg Joseph: Lehre der Augenkrankheiten, Wien, 1792, ii, p. 12. [14] Beer, Georg Joseph: Ansicht der Künstlichen Pupillen-Bildung, Wien, 1805, p. 105. [Illustration: Fig. 6.--Beer’s iridotomy with broad iris-knife (after Mackenzie).]