Incidence of Postoperative Obstruction at Different Sites of Lacrimal Canalicular Injury

Abstract

Sir:FigureInjury to the lacrimal canaliculus leads to scarring and stenosis, which in turn cause complete or incomplete obstruction of the canaliculus, and such patients present with epiphora. There is general agreement on the need for urgent primary microsurgical repair with silicone intubation,1 and the tube should remain in place for 3 to 6 months to prevent anastomotic stenosis. Even so, 6 to 15 percent of patients with canalicular laceration suffer from epiphora after silicone tube intubation.2 A combination of upper and lower canalicular injury, use of a pigtail probe, and failure to use silicone intubation are possible important factors that lead to postoperative canalicular obstruction.3 However, there is still no consensus on the causes of postoperative epiphora. The soft tissues along the canaliculus are not consistent. With increasing distance from the lacrimal punctum, more soft tissue surrounds the canaliculus.4 The first 4 mm of the canaliculus lies between the conjunctiva and the tarsal plate; subsequently, it travels deeper and enters the orbicularis muscle and passes under the medial canthal ligament into the lacrimal sac. Finally, the last 2 to 3 mm is deeper and is surrounded by the fibers of the lacrimal sac fascia. We can assume that the site of canalicular injury may be an important factor that predisposes the patient to postoperative canalicular obstruction and epiphora. We presume that sites close to the sac will have a higher incidence of scarring and stenosis and be more likely to induce postoperative obstruction. Forty-five patients with canalicular lacerations underwent urgent reparative surgery; bicanalicular silicone tube intubation was performed and the tube was retained for 3 months. The patients were divided into three groups on the basis of measurement of the distance from the punctum to the distal cut end of the canaliculus (i.e., distance): group A (distance, ≤4 mm), group B (5 mm ≤ distance ≤ 7 mm), and group C (distance, ≥8 mm). After 6 months, irrigation of the lacrimal passages was performed to evaluate the outcome. The incidence of postoperative obstruction in each group was analyzed statistically and compared by a cross-tabulation chi-square test (Table 1).Table 1: Incidence of Postoperative Canalicular Obstruction in the Three GroupsGroup A consisted of 15 patients, group B consisted of 21 patients, and group C consisted of nine patients. After 6 months, a total of four patients (8.9 percent) appeared to have obstruction, as evaluated by irrigation of the lacrimal passages: three in group A (20 percent), one in group B (5 percent), and none in group C. The incidence of postoperative canalicular obstruction was not significantly different (p = 0.074) between groups A and B (Fig. 1).Fig. 1: (Above, left) Measurement of the distance from the punctum to the distal cut end of the injured canaliculus; the lacrimal probe was used to brace the canaliculus and ensure the accuracy of the measurement. (Above, right) Identification of the proximal cut end of the canaliculus was the key to the surgical procedure; the black arrow indicates the proximal cut end, which lies close to the lacrimal sac. (Below, left) A 60-year-old man is shown with right lower canalicular laceration as a result of a blow, before repair of the canalicular laceration and silicone intubation surgery. (Below, right) The patient at 4 months after surgery.In contrast to the expected outcome, based on the anatomical characteristics of the canaliculus, the lowest incidence of postoperative canalicular obstruction was in group C; group A showed the highest incidence. We suspect that the presence of tissue surrounding the canaliculus was the reason for the high incidence of postoperative canalicular obstruction in group A. Serial histologic sections of a fetus at 14 to 16 weeks of gestation revealed that the extent of the envelope formed by the Horner muscle around the canaliculus decreases gradually from the lacrimal punctum to the lacrimal sac.5 However, further research is needed to prove this theory. WoDong Shi, M.D., Ph.D. Xianqun Fan, M.D., Ph.D. Department of Ophthalmology, Shanghai Ninth People's Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China PATIENT CONSENT The patient provided written consent for the use of his images. DISCLOSURE The authors have no financial interest in the methodology described in this article. There was no source of funds for this work. ACKNOWLEDGMENTS This work was sponsored by the Shanghai Leading Academic Discipline Project (S30205), the National Natural Science Foundation of China (30973279), and the Cooperative Foundation of Medical and Engineering Science of Shanghai Jiaotong University (project no. 40YG2009ZD102).