Final nasolacrimal ostium after external dacryocystorhinostomy.

OBJECTIVE To evaluate the nasolacrimal ostium created after successful external dacryocystorhinostomy. METHODS This prospective study included 41 successful primary external dacryocystorhinostomies performed in 41 patients with nasolacrimal duct obstruction (33 women and 8 men; age range, 19-75 years). The dimensions of osteotomy were measured during surgery. Patients alternately underwent either anterior only or anterior and posterior flap anastomosis between the lacrimal sac and the nasal mucosa. Digital subtraction macrodacryocystography was performed to assess the nasolacrimal ostium 6 months after surgery. RESULTS Dacryocystography showed that the lacrimal sac had re-formed in 40 (98%) of 41 patients. The nasolacrimal ostium was located at the inferior part of the re-formed sac in 37 patients (90%) and at the middle part of the re-formed sac in 3 patients (7%). Mean ostium heights were 3.8 mm (range, 1.6-6.5 mm) in patients who underwent anterior flap anastomosis and 3.1 mm (range, 1.2-5.2 mm) in those who underwent both anterior and posterior flap anastomosis (P =.22). Ostium height did not correlate with osteotomy size (mean, 183 mm2; range, 132-266 mm2; P =.10). CONCLUSIONS This study confirms that after successful dacryocystorhinostomy, the nasolacrimal anastomosis contracts into a relatively small ostium. Contrary to common belief, the lacrimal sac often re-forms after surgery. The final ostium frequently develops at the inferior part of the regenerated sac. Suturing the posterior lacrimal and nasal flaps in addition to the anterior flaps does not significantly affect the ultimate ostium size.