Alternative methods. The following methods have been practised:—
Simple incision across the fibres of the iris by means of Graefe’s or Knapp’s knife.
Division with scissors through a wound of the limbus.
By these two methods the opening produced is small, and is very liable to be closed by the subsequent cyclitis. The following operation yields more satisfactory results.
Kuhnt’s operation.
Instruments. Speculum, fixation forceps, Graefe’s knife, iris forceps and scissors.
First step. The surgeon, standing facing the patient, enters the anterior chamber about 2 millimetres inwards from the limbus at the junction of the middle and lower third of the cornea with a Graefe’s knife, the cutting edge directed downwards. The knife is then made to penetrate the iris and underlying capsule, and to travel beneath this to a similar point on the other side, where it is made to come back again into the anterior chamber by again penetrating the iris, and finally out again through the cornea. The knife is then made to cut out in a downward direction.
Fig. 104. Iridotomy by Ziegler’s Method. Showing the shape of the knife and the position of the first puncture in the iris; the cutting is performed by a sawing movement.