External dacryocystorhinostomy (DCR) #2
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This is Richard Allen at the University of Iowa.
The video demonstrates an additional example of an external dacryocystorhinotomy.
A marking has been made at the medial canthus extending from medial canthal tendon inferiorly toward the ala of the nose for 2 cm. A 15 blade is used to make an incision along the marking. One should be cognizant of the angular artery in this area. Stevens scissors are then used to bluntly dissect to the underlying periosteum. 4-0 Silk sutures are then placed through the edges of the incision. These sutures should be placed relatively deep to aid in visualization. Four sutures are placed around the incision. These sutures are particularly useful if you do not have an assistant to hold a lacrimal rake. The freer periosteal elevator is then used to expose and make an incision through the periosteum. The periosteum is then elevated to the level of the anterior lacrimal crest.
The lacrimal sac is then elevated from the lacrimal sac fossa. I will almost always disinsert the medial canthal tendon superiorly to aid in visualization. I have found that is has no untoward effect on subsequent medial canthal position post-opeatively. The posterior portion of the lacrimal sac fossa is identified where the thin bone resides. A Hardy sella punch is then used to remove the bone of the posterior lacrimal sac fossa. Once the bony ostium is large enough, a larger Kerrison rongeur can be used. A believe that the success of a DCR rests on making a large ostium, construction of mucosal flaps, and removal the bone of the ostium superiorly to the level of the medial canthal tendon; this is demonstrated here.
An adequate ostium has been performed and the underlying nasal mucosa is identified. A 66 Beaver blade is then used to make an incision along the lacrimal sac with vertical anterior incisions superiorly and inferiorly. Purulent material is identified, consistent with the patient's diagnosis of chronic dacryocystitis. The inside of the lacrimal sac can then be visualized. The Bowman probe is placed though the canalicular system and visualized. The posterior flap of the lacrimal sac is then constructed with Westcott scissors. The flaps for the nasal mucosa are then made with the Beaver blade. The anterior flap is developed, and the posterior flap is then developed with the Beaver blade and Westcott scissors. This should result in easy apposition of the posterior nasal mucosa flap to the posterior lacrimal sac flap.
A 5-0 chromic suture on half circle needle is then used to suture together the posterior flaps. Two sutures are usually adequate. The second suture is placed in the same manner to appose the posterior flap of the lacrimal sac to the posterior flap of the nasal mucosa. Crawford stents will then be placed through the system. This is retrieved from the nose in this case with a Crawford hook. The other arm of the stent is placed and retrieved from the nose in the same fashion. In order prevent post-operative prolapse of the stent a 4-0 silk suture is placed around the stents at the level of the lacrimal sac. The anterior flaps can then be sutured together over the Crawford stent with the same 5-0 chromic suture on a half circle needle. Again, I think two sutures are adequate.
The skin incision can then be closed with deep interrupted 5-0 Vicryl sutures placed in a buried fashion. Usually 2 to 3 sutures are adequate. Superficial sutures can then be placed with the suture choice of the surgeon. In this case, 5-0 fast-absorbing sutures are used in an interrupted fashion. The patient will use antibiotic ointment three times a day and the patient will return in one week for reevaluation.