4. _Wound of the lens._ The great safeguard against wounding the lens is to keep the point of the knife always superficial to the iris and in the periphery of the anterior chamber. If the lens be definitely wounded at the time of the operation it should be extracted immediately after the iridectomy. If the wound be only subsequently discovered (usually about the third or fourth day), provided the lens be not presenting in the wound, the eye should be allowed to settle down and the traumatic cataract extracted some time after the tenth day. 5. _Presentation of the lens in its capsule._ The lens may present in its capsule at the time of the operation or be found subsequently on the dressings. In the latter instance it is very liable to carry iris into the wound, and a cystoid cicatrix results. This accident is usually due to increased tension in the vitreous chamber; a large incision, especially if placed rather far back in the sclerotic, will also favour its occurrence. If the accident should happen to one eye, and acute glaucoma be present in the other, it is advisable to do a posterior scleral puncture before the iridectomy is performed. Partial dislocation of the lens forward may occur after the wound has healed, leaving the tension of the eye not reduced. This is a condition extremely difficult to recognize, and it is usually only discovered pathologically; if recognized clinically, extraction of the lens should be performed (Fig. 117). 6. _Intra-ocular hæmorrhage. Hæmorrhage into the anterior chamber_ occurs at the time of the operation and is readily absorbed; occasionally it may persist for a considerable time in cases of glaucoma of long standing. After the operation hæmorrhage may also occur from the cut margin of the iris, which never heals, viz. never becomes covered with endothelium. The hæmorrhage may occur as late as two weeks after the operation and may recur from time to time; it is especially liable to occur in old people with arterio-sclerosis. It is usually absorbed without giving rise to any trouble beyond delay in the convalescence. _Retinal hæmorrhages_ are frequent and usually small, but a considerable hæmorrhage may take place into the vitreous. As a rule these clear up satisfactorily unless the macular region be involved. [Illustration: FIG. 117. GLAUCOMA IRIDECTOMY. Failure to relieve the tension owing to displacement of the lens.]