目的　应用30o斜耳内窥镜镜头经鼻观察泪囊前泪道阻塞患者鼻泪管下口的形态，总结内窥镜下泪囊前泪道阻塞患者鼻泪管下口的影像解剖形态特征，为临床开展经鼻泪管下口逆行插管造影检查打下基础。  方法　选取患有泪囊前泪道阻塞性疾病患者54例（75眼），上下泪点闭锁3例（5眼）、上下泪小管阻塞15例（24眼）、泪总管阻塞18例（28眼）、陈旧性上下泪小管断裂18例（18眼），均应用30°斜耳内窥镜镜头观察鼻泪管下口，总结活体泪囊前泪道阻塞患者鼻泪管下口的形态特点。  结果　54例（75眼），66眼鼻泪管下口开放，开放率88%，其中1例鼻泪管下口开放者，受刺激后，Hanser瓣膜完全遮盖鼻泪管下口，导致其呈线形关闭；9眼鼻泪管下口闭锁，占12%。根据鼻泪管下口开放的形态将其分为椭圆形宽大状（30眼，45.45%）、三角形裂隙状（12眼，18.18%）、条形裂隙状（24眼，36.36%）三种类型。21例（42眼）双眼患病的患者，双侧鼻泪管开口形态不同者15例（30眼，71.42%），双侧鼻泪管开口形态相同者6例（12眼，28.57%）。  结论　应用30°斜耳内窥镜镜头经鼻观察泪囊前泪道阻塞患者的鼻泪管下口的可行性好，对于鼻泪管下口开放的患者有进行内窥镜引导下的逆行插管造影检查的解剖基础。

Objective　To observe the morphology of the inferior orifice of the nasolacrimal duct of the patients with presaccular lacrimal obstruction by using 30o ear endoscope and provide the basis for the CT retrograde intubation dacryosystography.　Methods　54 patients (75 eyes) with presaccular lacrimal obstruction from May 2011 to March 2012 were involved in this study, including 3 cases (5 eyes) of upper and lower lacrimal punctum atresia, 15 cases (24 eyes) of superior and inferior canalicular obstruction, 18 cases (28 eyes) of common canaliculus obstruction, 18 cases (18 eyes) of previous laceration of superior and inferior canalicular. All patients underwent the endoscopy by using 30o ear endoscope and the imaging characteristics of the inferior orifice of nasolacrimal duct was obtained.     Results    54 subjects (75 eyes) participated in the study, 66 eyes were confirmed that the inferior orifice of nasolacrimal duct was opening, the opening rate being88% (Of  the 66 eyes, stimulated Hanser valve of 1 case covered the orifice of nasolacrimal duct and led to linear closure of the orifice) . 9 eyes were confirmed the atresia orifice of nasolacrimal duct，accounting for 12%. According to the shape of the inferior orifice, it was divided into three types: oval large (30 eyes, 45.45%), triangular fissure (12 eyes, 18.18%), strip fissure (24 eyes, 36.36%).In the 21 cases (42 eyes ) of the binocular sick patients, 15 cases  (30 eyes, 71.42% ) of different forms and 6 cases （12 eyes，28.57%）of the same forms of bilateral opening inferior orifice of the nasolacrimal duct.    Conclusion　It is practicable to observe the location and morphology of the opening inferior orifice of the nasolacrimal duct for the patients