[Illustration: FIG. 161. MODIFIED DIEFFENBACH’S OPERATION TO REPLACE THE LOSS OF THE WHOLE LOWER LID. _First step._ The whole lower lid, together with the growth, is removed by the V-shaped incision and the flap to form the new lid is dissected up from the outer canthus. The diagram shows the incision marking out the flap.] [Illustration: FIG. 162. MODIFIED DIEFFENBACH’S OPERATION. _Third step._ Showing the flap turned down, to the free border of which is attached the flap of skin and ear cartilage. The inset shows the proportion of skin and cartilage (light area) to be removed from the back of the ear.] _Fourth step._ The flap forming the new lower lid is sutured in position. The surface from which the flap is taken is closed as far as possible with sutures after undermining the edges, any raw area being covered by skin grafts taken from the arm. CHAPTER X OPERATIONS UPON THE LACHRYMAL APPARATUS Operations upon the lachrymal apparatus are divided into-- I. Operations upon the lachrymal canals. II. Operations upon the lachrymal gland. The majority of operations are undertaken for the relief of obstruction to some portion of the canal which leads from the conjunctival sac to the nose, obstruction to which causes an overflow of tears (epiphora)--a condition which must be distinguished from hypersecretion (lachrymation). The obstruction may occur in any part of the canal, that is to say, in the puncta, canaliculi, lachrymal sac or duct; and it is most important to determine the cause and position of the obstruction in every case before undertaking an operation for its relief. Hence it need hardly be said that the nose should be carefully examined in every case unless the cause is obvious. The operations are divided into two classes:-- 1. Those which are undertaken for the relief of the obstruction. 2. Those which are undertaken for the obliteration of the canals. Except under exceptional circumstances, the latter operations are only undertaken when a cure cannot be brought about by the former. The presence of a septic focus, such as a distended lachrymal sac, apart from the irritation and increased lachrymal secretion caused thereby, is a source of grave danger to the eye if not relieved, as it is a frequent cause of serpiginous corneal ulceration. OPERATIONS FOR THE RELIEF OF LACHRYMAL OBSTRUCTION DILATATION OF THE CANALICULUS =Indications.= (i) Contraction of the puncta following marginal blepharitis, especially when associated with ectropion. (ii) Preparatory to syringing or probing. (iii) To dilate a stricture of the canaliculus. =Instruments.= Nettleship’s canaliculus dilator (Fig. 163). =Operation.= The operation is performed under adrenalin and cocaine, a little solid cocaine being rubbed in over the canaliculus.