Immediate. 1. If the knife-point become entangled in the iris as it is passed across the anterior chamber it should be slightly withdrawn, if this can be done without loss of aqueous, the iris being thereby disengaged.[4]
2. Loss of the aqueous before the section is complete may result in the entanglement of the iris as before described, or the iris, owing to the presence of the aqueous in the posterior chamber, may bulge forward in front of the knife-blade. The latter complication is more likely to occur if the section be made too rapidly. The iris may sometimes be disengaged by depressing the handle of the knife towards the patient’s chin and raising the blade towards the cornea so as to allow the aqueous in the posterior chamber to escape. If this cannot be accomplished, the section should be completed and the iris, which may be divided by the knife, removed subsequently when doing the iridectomy.
3. Avulsion of the iris due to movement of the patient’s head. This is more liable to take place if the eye has not been properly cocainized some time before the operation. The grasping of the iris by the forceps is always felt by the patient to a certain extent, and he should be warned not to move. Avulsion is usually not complete and only results in a larger iridectomy than was intended.
4. Dislocation of the lens. (a) When opening the capsule, either from too great pressure of the capsule forceps, or from the patient moving his head. The lens must then be delivered by the vectis. (b) If, in delivering the nucleus, the upper edge is not made to present by pressure on the lower part of the cornea, the nucleus, especially if it be small, is liable to be dislocated upwards beyond the incision. It must then be removed with the vectis. In cases where a small nucleus is suspected, pressure should be made on the sclerotic above the incision with a curette, as well as on the lower part of the cornea, so as to make the nucleus present in the wound.
The lens may be dislocated backwards into the vitreous; if this should happen and the lens cannot be delivered, the flap must be replaced in position and the eye bandaged. Unfortunately this complication is usually followed by irido-cyclitis and loss of the eye.
5. Loss of the vitreous. There are two chief phenomena which may indicate that loss of vitreous is about to take place after the extraction of the lens.
(a) The wound gapes unnaturally after the expulsion of the lens, and the clear vitreous may be seen presenting in the wound in the still unruptured hyaloid membrane.
(b) There may be an apparent deepening of the anterior chamber owing to the fluid vitreous making its way forward through the ruptured hyaloid into that cavity.
If the vitreous presents in the wound before the lens has been removed, the latter should be delivered as rapidly as possible by the vectis, as has previously been described.
If the vitreous be lost or one of the phenomena previously mentioned occurs after the delivery of the lens, the speculum should be removed from the eye and the conjunctival flap replaced in position as quickly as possible. The eyelid is then carefully raised from the surface of the eyeball by means of the lashes held in the finger and thumb and carried downwards over the globe until it is in the closed position, and a bandage is then applied.