Operation. It is usually performed on the lower canaliculus. The eye is cocainized as in the previous operation and the patient is made to look up.
First step. The canaliculus is first dilated. The knife is inserted for a short distance with the handle parallel to the lid margin. The lower lid being held on the stretch by the thumb, the handle of the knife is raised towards the brow, thus dividing the canaliculus. The blade of the knife should be directed upwards and slightly backwards.
Second step. As the lips of the wound are liable to reunite, it is better to remove the posterior lip of the groove. This is performed by seizing the latter with forceps and dividing it with scissors. The entrance to the canaliculus should be kept open by means of the dilator passed twice a week for a month.
SYRINGING THE LACHRYMAL DUCT
Indications. (i) To test whether the lachrymal canals are patent.
(ii) By constantly cleansing the sac and washing away all purulent discharge the mucous membrane may regain a more healthy condition, and so an obstruction due to an alteration in the mucous lining may be relieved. In cases with a purulent discharge a small quantity of protargol (10% solution) may be left in the sac after syringing.
(iii) The injection of adrenalin and cocaine into the sac before its excision.
Fig. 165. Lachrymal Syringe.
Operation. The eye is cocainized and the patient made to look up. The punctum is everted by pulling down the lower lid. The canaliculus is then dilated. The nozzle of the lachrymal syringe (Fig. 165) should be passed until it is felt to impinge on the bony outer wall of the sac. Withdraw the syringe slightly and apply gentle pressure to the piston. The fluid will either regurgitate through the upper canaliculus or, if the duct be patent, pass down into the nose and so into the throat.