Corneal flap incision for cataract operation.

One of the drawbacks of all classical incisions for cataract surgery has been the slow consolidation of the scar. According to Dunnington (1956) and to Ashton and Cook (1951), the first step in the healing of limbal wounds is taken by the swelling of the corneal lamellae, whereas the sclera plays a very passive role in the process. The retractability of the tissues then leads to a separation of the anterior from the posterior margin; a condition that is soon overcome anteriorly by epithelial proliferation, but which leaves a cleft posteriorly that has been demonstrated in monkeys up to 2 weeks after the operation. Gliedman and Karlson are said by Dunnington (1956) to have proved that the tensile strength of limbal wounds (sutured and without a conjunctival flap) amounts to only 6-5 per cent. of the normal (i.e. undisturbed limbal tissue) in the immediate post-operative period, to 15-4 per cent. of it on the ninth post-operative day, to 34 per cent. on the fourteenth day, and still only to 62 per cent. 6 months after the operation. In the light of these findings, the necessity for an incision that would overcome this difficulty appears quite obvious. The technique to be described below is based on Wheeler's halving principle, in the sense that the superficial part of the incision does not coincide with the deeper part of the same. The incision is made wholly on corneal tissue on the assumption that such a wound, if properly sutured, would develop a greater tensile strength, thus preventing those untoward post-operative occurrences known to derive from sluggish limbal healing. These theoretical considerations have yet to withstand the test of experimental work, but over eighty cases of senile cataract operated on by this method seem to substantiate them.