Cataract Extraction with Alpha-chymotrypsin a Controlled Trial.

First fifty intracapsular extractions were performed in an uncontrolled series so that the operator should become thoroughly familiar with the technique. In order to make a true assessment fifty ampoules were prepared by the hospital pharmacist with their accompanying ampoule of diluent, and these were numbered 1 to 50. Some of the ampoules contained active A.C.T. and the others an inert substance. The numbered labels were so wrapped round that it was impossible to see into the ampoule and there was no way of knowing whether an active or inert substance was introduced into the eye. Case notes were made after each operation and the key was kept in a sealed envelope and not referred to until the end of the complete series. All cases were operated upon under general anaesthesia, and the section was a small von Graefe section enlarged with scissors without a conjunctival flap. One pre-placed groove suture and four post-placed sutures were inserted. After the introduction of the unknown solution and the recommended wait of 3 minutes, the iris was fully retracted under the raised cornea and the lens grasped tangentially at 12 o'clock as near as possible to the equator with Arruga's forceps under direct vision.