Even in man these parts are remarkably free from disease, while in the lower animals, we have literally no record of such conditions. Inflammation of the gland (dacryo-adenitis) would be manifested by a sensitive swelling under the outer part of the orbital process, and upper eyelid and by lachrymation, and obstruction of the gland duct and by a tense transparent rounded swelling inside the lid. A fistula is possible from a penetrating wound of the lid in the same situation. In both of the latter conditions an opening made through the palpebral conjunctiva will allow the discharge of the tears in the proper place, and healing of any external wound may be hastened by suture or plaster.
OBSTRUCTION OF THE LACHRYMAL PUNCTA. ATRESIA. INFLAMMATION.
Congenital atresia of these puncta has been recorded in foals, by Hollmann and obstruction as the result of inflammation, by Lafosse, Verjaus and Tyvaert, and of the entrance of the seeds of bromus by Stockfleth.
Apart from congenital atresia and impaction of foreign bodies the symptoms are those of conjunctivitis, with escape of tears over the face (epiphora). Injection of aseptic water into the lower puncta and its escape by the upper, and by the nasal orifice, will determine the patency or otherwise of the various channels.
Treatment consists in astringent collyria to check the inflammation, in the removal of any foreign body, in the dilation or slitting of the lachrymal canaliculi, and in case of complete atresia, in incising the lachrymal sac. Slitting of the canaliculi is accomplished by a small probe pointed bistuory (canaliculus knife). The lid is drawn away from the carnucle, and the probe point inserted at first downward, then inward and backward, and when it is well inside the sac the handle is brought to the vertical and the walls of the duct slit open.
In case of atresia Leblanc recommends to seize the inner canthus with rat tooth forceps so as to include the structures about the sac and to plunge the bistuory directly into the sac. Then by the aid of a whalebone staff he passes three silk threads through the duct and fixes them in place by attaching them to a copper ring at each end. This is retained in place and moved daily until the passage has been definitely healed and its permanency assured.
WOUND AND FISTULA OF THE LACHRYMAL SAC.
The lachrymal sac, which receives the tears from the canaliculi, is situated in the infundibulum at the upper end of the lachrymal canal and is in great measure protected against external injuries by the prominent orbital edge of the lachrymal bone. Yet violent blows with or without fracture, sometimes lead to rupture of the mucous walls and the formation of a fistula. Wounds made with penetrating bodies, more or less pointed are also liable to involve the sac. The fistulous orifice may be through the skin at the inner canthus or through the mucosa by the side of the carnucle. The cutaneous opening may be a minute orifice from which tears and muco-purulent matter escapes, to mat together the hairs on the side of the face. Sometimes there is a reddish elevation, the size of a pin head, and in fistula through the mucosa this is the rule, and the orifice is elevated so that the tears flow out over the face. For the symptoms of the attendant catarrh of the sac see below. In infected cases with obstruction of the lachrymo-nasal duct, it has been known to extend to the bone and even to open into the sinuses, or tooth follicles. (Gerard, Leblanc).
The condition is found in horses, cattle and dogs.
Treatment. In fistula resulting from simple traumatism, nothing more may be requisite than rest and soothing astringent applications. Sutures are sometimes resorted to but are liable to cause itching and do more harm than good. It is above all important to keep the lachrymo-nasal duct patent, and for this purpose a lead or silver stilet, or a thick catgut suture may be worn in the canal until healing has ensued.