=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. =Complications.= If too forcible syringing be used extravasation of the fluid may take place. This is accompanied by pain and swelling in the lachrymal region. It usually subsides under hot fomentations, but suppuration and even cellulitis of the orbit have been known to occur. PROBING THE LACHRYMAL DUCT =Indications.= (i) In cases of congenital lachrymal obstruction due to débris blocking the duct. (ii) When syringing has failed to bring about a cure, a probe may be passed once or twice to see if dilatation causes any improvement. It is especially useful in children. (iii) As a preliminary to the insertion of styles. Various forms of probes are employed, those of Bowman being in general use. Too fine a probe should not be used, otherwise a false passage is liable to be made. =Operation.= This is performed under adrenalin and cocaine, which should be injected into the lachrymal sac. The lower punctum is dilated and the probe passed parallel to the lid margin until it is felt to impinge upon the lachrymal bone. Keeping the point applied to the bone, the handle of the probe is rotated upwards through rather more than a quarter of a circle and passed by a gentle pressure downwards and slightly outwards into the duct, keeping the point of the probe close to the bone the whole way. The direction of the probe after entering the duct should be downwards, outwards, and backwards in the direction of the first molar tooth on the same side. The backward direction of the duct is much more marked in young children than in adults. =Complications.= A false passage may be made into the antrum of Highmore. If such an accident should occur, no further attempt should be made to pass a probe for a few days until the wound has healed. THE INSERTION OF STYLES A few surgeons still insert styles into the lachrymal duct with the idea of continuous dilatation. The hollow styles used by Bickerton are the ones most frequently employed. =Instruments= for dilating, slitting the canaliculus, probing, and styles. Also Stilling’s knife. =Operation.= A general anæsthetic is desirable. _First step._ The canaliculus is dilated and slit up, the posterior lip being removed (see p. 29). _Second step._ The duct is dilated by probing (_vide supra_) or enlarged by passing Stilling’s knife down it.