Cystotome

In the ordinary capsulotomy some of the difficulties come from the instrument itself but more and greater ones from the conditions under which it must be used. The straight capsulotome is kept sharp with difficulty. It cuts only when drawn toward the operator, at right angles to this it simply scratches. As soon as the section is made the iris contracts, the lens comes forward and the anterior chamber is abolished. Into this narrow space must be passed a straight instrument between cornea and lens; it is impossible to do this and reach below the center of the lens without pressing it more or less backward and at this stage the lens, held only by its suspensory ligament, is mobile and easily dislocated. More than this, the operator in his zeal to make an efficient opening in the capsule is apt to rupture this ligament and loss of vitreous ensues. There are no means of knowing that the capsulotomy has been inadequately performed until the lens, when pressure is applied to the globe, refuses to present in the section. In this event either the fixation forceps must be reapplied, a difficult and dangerous thing to do on an opened eye, or the cystotome reintroduced without its help trusting to the patient keeping still. The pupillary space being narrowed by the contraction of the iris leaves insufficient room to work in and it is a difficult matter not to wound the iris or entangle it in the tip of the instrument. If the bent cystotome of Knapp is used then are these difficulties enhanced and not only is there greater difficulty in removing fragments of cortex but a peripheric capsulotomy leaves two thicknesses of lens capsule in the pupillary space and more often is required a secondary operation. Should blood enter the anterior chamber then are the difficulties before mentioned still further increased.

Then, again, the capsule may be insufficiently incised, or not opened at all. The surgeon generally discovers this failure when, on pressure, he finds that the lens moves slightly but makes no actual progress towards a complete exit. In that event, a very sharp cystotome should be used a second time. As mentioned before, the capsule of Morgagnian cataracts is extremely difficult to cut even with a proper capsulotome. Difficulty is to be expected with very opaque capsules, especially when they present a large, white, dense, circumscribed opaque area. Having been forewarned by these appearances the surgeon will employ a very sharp cystotome, using cautiously a little more force than usual, tearing the capsule if needed. Should vitreous escape in front of the lens and the latter sink backward into the vitreous the best plan is to finish the operation by means of a wire loop or vectis. This procedure does not necessarily increase the vitreous loss.