The cavernous body of the human efferent tear ducts contributes to regulation of tear outflow

PURPOSE: To test the hypothesis that the surrounding vascular plexus of the lacrimal sac and the nasolacrimal duct contributes to the regulation of tear outflow. METHODS: Experiments in 30 probands aged between 15 and 37 years were performed in both nasolacrimal systems of each subject by observing with an endoscope the transit time of an applied tear drop containing fluorescein dye until its entry into the inferior meatus of the nose. Four different experiments were performed to determine the median transit time under normal conditions and the influence on transit time of a decongestant drug, a foreign body on the ocular surface, and a decongestant drug applied together with a foreign body on the ocular surface. Comparisons were made between the right and left nasolacrimal system, in males and females, eyeglass wearers and non-eyeglass wearers, and the different experiments and the results statistically analyzed. RESULTS: The tear transit time was independent of side (right or left), gender, or eyeglass wear. It showed great individual variability. Application of a decongestant drug or placement of a foreign body on the ocular surface both prolonged the dye transit time significantly. Application of a decongestant drug simultaneously with placement of a foreign body shortened the dye transit time significantly compared with the effect of the decongestant drug alone but revealed no significant difference compared with application of a foreign body alone. CONCLUSIONS: The cavernous body of the lacrimal sac and nasolacrimal duct plays an important role in the physiology of tear outflow regulation. It is subject to autonomic control and is integrated into a complex neuronal reflex feedback mechanism starting with the dense innervation of the cornea. Moreover, its function can be pharmacologically influenced.     

Drainage of tears: impact on the ocular surface and lacrimal system

The human efferent tear ducts are part of the lacrimal system. Because little knowledge exists concerning the physiology of the nasolacrimal system, and hence its patho- physiology, the nasolacrimal system has received almost no consideration as a possible factor in dry eye. The human nasolacrimal ducts consist of the upper and the lower lacrimal canaliculus, the lacrimal sac, and the nasolacrimal duct. As a draining and secretory system, the efferent tear ducts play a role in tear transport and nonspecific immune defense. Moreover, components of tear fluid are absorbed in the nasolacrimal passage and are transported into a surrounding vascular system. This system is similar to a cavernous body that is subject to autonomic control and regulates tear outflow. Tear duct-associated lymphoid tissue (TALT) is present in the efferent tear ducts, displaying the cytomorphological and immunophenotypic features of mucosa-associated lymphoid tissue (MALT). Under normal conditions, tear fluid components are constantly absorbed into the blood vessels of the surrounding cavernous body. These vessels are connected to the blood vessels of the outer eye and could act as a feedback signal for tear fluid production, which ceases if these tear components are not absorbed. In this way, dry eye could be initiated. Defective stimulation of TALT could result in abnormal immune deviation at the ocular surface, leading to an autoimmunological response that causes dry eye pathology.     

Anatomie und Physiologie der ableitenden Tränenwege

The human nasolacrimal ducts consist of the upper and lower lacrimal canaliculi, the lacrimal sac and the nasolacrimal duct and drain tear fluid from the ocular surface into the nose. The lining epithelium of the lacrimal sac and the nasolacrimal duct is lined by microvilli supporting the hypothesis that tear fluid components are absorbed. Based on its composition epithelial secretions fulfill functions in tear transport and antimicrobial defense. Further defense mechanisms are displayed by IgA and defense cells which show a special intraepithelial and subepithelial distribution. Moreover, tear duct-associated lymphoid tissue (TALT) is present, displaying the cytomorphological and immunophenotypic features of mucosa-associated lymphoid tissue (MALT). The mechanisms of tear outflow are not yet resolved and several hypotheses exist. Significance is attributed to the lacrimal part of the orbicularis eye muscle surrounding the canaliculi, the helically arranged system of connective tissue fibres and the cavernous body that surrounds the lacrimal sac and the nasolacrimal duct. Moreover, the cavernous body has a function in protecting the lacrimal passage and is active during emotions.     

Functional anatomy of the human efferent tear ducts: a new theory of tear outflow mechanism

· Background: The mechanism of lacrimal drainage under physiological conditions is controversial. The aim of this study was to analyze the three-dimensional architecture of human efferent tear ducts from functional and clinical points of view. A new theory of tear outflow is discussed. · Methods: Thirty-two prepared lacrimal systems of adults were examined by histological, immunohistochemical and scanning electron microscopic techniques. · Results: The wall of the lacrimal sac is made up of collagen bundles, elastic and reticular fibers arranged in a helical pattern. Wide luminal vascular plexus are embedded in this helical system and connected to the cavernous tissue of the inferior turbinate in the region of Hasner’s valve. Immunohistochemical analysis showed evidence of type I and type III collagen as well as chondroitin 4- and 6-sulfate. · Conclusion: With blinking, the lacrimal part of the orbicularis muscle contracts. The fornix of the sac moves in a cranial-lateral direction. Thus the lacrimal sac distends and may be ’’wrung out’’ due to its medial attachment and helically arranged fibrillar structures. The vascular plexus may play an important role in the absorption and drainage of lacrimal fluid. Received: 23 January 1998 Accepted: 27 March 1998     

Ableitende Tränenwege und Trockenes Auge

BACKGROUND: The knowledge regarding the pathogenesis, diagnosis, and treatment of dry eye has made large advances in recent years. However, many questions are still unanswered. Although the nasolacrimal ducts are part of the tear system they have been paid nearly no attention regarding dry eye. METHODS: The present knowledge about the nasolacrimal ducts is presented and discussed in a context with dry eye. A PubMED search was conducted for articles published from 1966 to the present; in addition, review articles as well as book chapters were considered and discussions with investigators in the field were performed. RESULTS: As a draining and secretory system, the nasolacrimal ducts play a role in tear transport and non-specific immune defense. Moreover, components of tear fluid are absorbed in the nasolacrimal passage and are transported into a vascular system that surrounds the nasolacrimal sac and nasolacrimal duct. This system is comparable to a cavernous body and it is connected to the blood vessels of the outer eye. Also it is subject to vegetative control. Organized mucosa-associated lymphoid tissue (MALT) is present in the nasolacrimal ducts displaying the cytomorphological and immunophenotypic features of MALT. CONCLUSIONS: The normally constant absorption of tear fluid components into the blood vessels of the surrounding cavernous body that are connected to the blood vessels of the outer eye, could be a feedback signal for tear fluid production, which comes to a halt if these tear components are not absorbed. Thus, dry eye could be initiated. Defective stimulation of tear duct-associated lymphoid tissue (TALT) could result in abnormal immune deviation at the ocular surface leading to an autoimmunological response that causes dry eye pathology.     

Falk's technic of extranasal dacryocystorhinostomy in cases of tear duct stenoses (author's transl)]

The lacrimal sac is totally sacrificed and rebuilt into an accessory nasal sinus using the extranasal dacryocystorhinostomy in the treatment of nasolacrimal duct stenosis as described by Falk in 1961. Using this method, 62 patients with tear duct stenoses were operated in our clinic since 1959. According to etiology, the stenoses were in 5 cases connatal, in 17 traumatic, in 32 inflammatory and in 8 iatrogenic. In only 4 cases (6,4%) failures were reported. - the operative indication has at present been expanded to include stenosis of the lower tear ducts (presaccal stenosis) or in cases where the lacrimal sac has been obliterated (saccal stenosis). In these cases the stenosis is dissected and a silicon tube (introduced via the tear point into the inferior lacrimal duct and drained into the nose) is left in position.     

Contribution of MRI in the dynamic study of the lacrimal outflow system]

PURPOSE: To evaluate a new magnetic resonance imaging protocol for dynamic study of the lacrimal outflow system and to use this protocol to search for problems in patients with an assumed permeable outflow system who develop epiphora. PATIENTS AND METHODS: A prospective study of nine patients, including 2 asymptomatic controls was conducted. The magnetic resonance protocol included, gadolinium instillation into the conjunctival cul-de-sac, 3D gradient-echo T1-weighted acquisition, 2 mm thick images passing through the nasolacrimal duct, dynamic acquisition after gadolinium instillation for timing dye progression through the outflow system. RESULTS: Similar results were obtained for the two control subjects with lacrimal transit time of a median 100 seconds. Three distinct events were individualized gadolinium arrival in the lacrimal sac (t1), at the extremity of the bony portion of the lacrimal duct (té), and the extremity of the mucosal portion of the duct (t3). Patients with an assumed permeable outflow system who had epiphora show results intermediary between passed dye and total blockage of the dye within the lacrimal sac. CONCLUSION: The study of the lacrimal outflow system using this new magnetic resonance imaging protocol contributes to the physiological study of tear evacuation and could be useful for quantitative assessment of lacrimal stenosis, particularly interesting for therapeutic guidance.     

Animal model for the absorption of lipophilic substances from tear fluid by the epithelium of the nasolacrimal ducts

PURPOSE: To compare the nasolacrimal tissues of several species to see how closely they resemble the human and to measure nasolacrimal absorption of a substance, to show that an absorption pathway exists for substances placed in the external eye, other than directly through the cornea or conjunctiva. METHODS: The nasolacrimal systems of six different vertebrates were investigated by light microscopy to find a species with a nasolacrimal system comparable to that of humans, for use in absorption experiments. In addition to primates, rabbits were revealed by histology to have a lacrimal system closely comparable to that of humans. The rabbit lacrimal system had a stratified epithelium consisting of two layers. Subepithelially, the lamina propria was composed of two strata: loose connective tissue containing elastic fibers and lymphatic cells and a rich venous plexus comparable to a cavernous body. Rabbits were therefore chosen for the absorption experiments. (3)H-cortisol was dropped into the eyes of female rabbits. After 21, 43, or 146 minutes, the rabbits were killed, the blood collected, and the nasolacrimal systems prepared and embedded for histologic examination. Serum was obtained from the clotted blood, and radioactivity was counted. Autoradiographs of sections of rabbit nasolacrimal duct were also prepared. RESULTS: Uptake of radioactivity into the serum was high and increased with time. After 21 minutes, maximum incorporation of the applied radioactivity into the blood the level was 7.1%; after 43 minutes, 12.4%; and after 146 minutes, 15.5%. Transport of radioactivity was visualized in autoradiographs of rabbit nasolacrimal systems. CONCLUSIONS: (3)H-cortisol is incorporated from the nasolacrimal ducts into the blood of rabbits. The comparable morphology of rabbits and humans suggests that absorption of cortisol would also take place in humans. Future investigations of the nasolacrimal passage are needed to understand whether absorption of normal tear fluid components in the nasolacrimal ducts is a physiological function that also plays a role in pathologic conditions such as dry eye. The similarities between rabbit and human nasolacrimal ducts support the use of the rabbit for such studies.     

Lacrimal sac cyst: apropos of a case]

A 17-year-old girl presented a unilateral cyst of the lacrimal sac. Epiphora was induced by compression of the patent lacrimal duct. The bony nasolacrimal canal was enlarged on the affected side. At pathology examination, the epithelium of the cyst wall was identical to the sac epithelium.     

外伤性泪道阻塞的CT检查

目的　探讨外伤性泪道阻塞的CT检查方法并分析其检查结果。方法　采用CT轴位扫描、冠状扫描及三维重建的方法 ,分析 12例泪道外伤的CT检查和结果。结果　CT轴位扫描良好显示泪囊和鼻泪管断面 ,冠状CT显示周围组织合并损伤 ,三维重建则直观显示泪囊窝和上颌骨额突骨折情况。CT显示外伤性泪道病变包括 :泪囊区软组织增厚、密度增高、泪囊扩张 ,泪囊区异常骨碎片影 ;泪囊窝和鼻泪管凹陷性、粉碎性和线性骨折 ;鼻泪管密度增高。结论　泪道CT轴位扫描、冠状扫描及三维重建可良好显示泪道及其周围组织的外伤情况 ,可用于诊断和进行手术设计。     

Tricompartment model of the lacrimal pump mechanism.

BACKGROUND: The role of the lacrimal sac in the lacrimal pump mechanism is controversial. METHODS: Movements of the lateral wall of the lacrimal sac with blinking were videotaped through an endoscope in eight patients after dacryocystorhinostomy. In addition, movements of an air bubble at the opening of the nasolacrimal duct with blinking were studied in three patients with an incompetent valve of Hasner. RESULTS: The superior half of the lateral wall of the lacrimal sac moved laterally with lid closure and medially with lid opening. The inferior half of the lateral wall of the lacrimal sac moved medially with lid closure and laterally with lid opening. In patients with an incompetent valve of Hasner, the air bubble at the opening of the nasolacrimal duct bulged into the nose with lid closure and retracted into the nasolacrimal duct with lid opening. CONCLUSIONS: A tricompartment model of the lacrimal pump is presented that incorporates these findings. With lid closure, the orbicularis muscle contracts, compressing the canaliculi and pulling the superior half of the lateral wall of the lacrimal sac laterally. This creates a lower pressure in the superior sac, allowing tears to be propelled from the canaliculi into the sac. At the same time, the inferior half of the lateral sac wall moves medially, creating a positive pressure in the inferior sac and nasolacrimal duct, thus forcing tears down the duct into the nose. With lid opening, the orbicularis muscle relaxes, allowing the canaliculi to open and the superior half of the lateral sac wall to move medially. The resulting negative intracanalicular pressure allows tears to flow from the lacrimal lake into the canaliculi, and the higher pressure in the superior sac closes the valve of Rosenmueller and forces tears from the superior to inferior sac and proximal nasolacrimal duct. At the same time, the inferior half of the lateral sac wall moves laterally, resulting in a negative pressure in the inferior sac and nasolacrimal duct.     

Changes in lumen width of nasolacrimal drainage system after adrenergic and cholinergic stimulation

PURPOSE: To determine the effect of an adrenergic agonist and a cholinergic agonist on the lumen width of the nasolacrimal drainage system. DESIGN: Prospective, nonrandomized, clinical trial. METHODS: The asymptomatic sides of 33 patients (23 women, 10 men) with unilateral stenosis/obstruction of the nasolacrimal drainage system were studied. The tear meniscus height of the asymptomatic side was normal, with a patent lacrimal system as revealed by dacryocystography. The nasolacrimal drainage system of the asymptomatic side was infused with 100 microL of 5% phenylephrine hydrochloride (an alpha-1 adrenoceptor agonist) or 100 microL of 2% pilocarpine hydrochloride (a cholinergic agonist), and dacryocystography was performed to determine the lumen width of the nasolacrimal drainage system. RESULTS: Phenylephrine caused a significant increase of the lumen width of the nasolacrimal drainage system, and the changes were more marked in the nasolacrimal duct (NLD), especially the upper and middle regions, than in the lacrimal sac. In contrast, pilocarpine reduced the lumen width of the NLD significantly, especially in the middle and lower regions, and the lumen width of the lacrimal sac was not significantly changed. CONCLUSION: The alterations of the lumen width of the nasolacrimal drainage system, especially the lumen width of the NLD by adrenergic and cholinergic agonists, suggest that the lumen width can be changed by the autonomic nervous system.     

先天性鼻泪管阻塞首次探通失败再治疗的临床分析

目的：分析我院就诊的28例首次泪道探通失败的先天性鼻泪管阻塞病例资料,总结再治疗策略。

方法：回顾性研究,选取2013-02-01/2017-12-31在我院就诊的591例患儿中的28例,均为首次泪道探通失败的先天性鼻泪管阻塞患儿(不包括外伤性和先天性泪道畸形),收集病史、鼻腔情况、首次探通年龄,治疗前后情况等病例资料。

结果：患儿28例中,15例经再次泪道探通联合置管术,取管后已治愈; 10例患儿经下鼻甲处理后,再次泪道探通联合置管术,取管后已治愈; 2例患儿经常发作急性泪囊炎,在全身麻醉下行鼻内窥镜下鼻腔泪囊吻合术; 1例骨性鼻泪管狭窄和阻塞患儿,有溢泪不伴溢脓,建议定期随访,13岁后鼻窦发育完全后行鼻内窥镜下鼻腔泪囊吻合术。

结论：先天性鼻泪管阻塞首次泪道探通失败再治疗需采取个性化的阶梯治疗方案,合理治疗该疾病。     

How do tears drain? Technetium studies.

We examined the tear drainage system of twenty-fiv normal volunteers by scintillography with Technetium Tc 99m (Pertechnetate). We photographed the changes occurring in the lacrimal sac and nasolacrimal duct during closure and opening of the eyelids. Our findings support Jones' views of normal tear drainage. The tracer was concentrated in the lacrimal sac while the lids were closed for 3 minutes and descended into the nasolacrimal duct as soon as they opened.     

Clinical efficacy of the polyurethane stent without fluoroscopic guidance in the treatment of nasolacrimal duct obstruction

PURPOSE: To evaluate the clinical efficacy of the polyurethane (Song) stent in the treatment of nasolacrimal duct obstruction without fluoroscopic guidance, especially at the junction between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: This study evaluated 59 cases of nasolacrimal duct obstruction in 53 patients, with mean epiphora of 36 months (range, 2 months-17 years). METHODS: Without the assistance of a radiologist, a polyurethane nasolacrimal stent was placed by introducing a guidewire through the superior or inferior punctum into the canaliculus and advancing it across the obstruction into the opening of the inferior meatus of the nasal cavity. The mean follow-up period was 22 months (range, 12 months-48 months). MAIN OUTCOME MEASURES: Patency of the lacrimal passage to irrigation and the duration of this procedure. RESULTS: Complete resolution of epiphora was accomplished in 55 (93.2%) of the 59 eyes. There was recurrence of epiphora in four cases because of obstruction of the stent in three cases and obstruction of the common canaliculus by recurrent dacryocystitis in one case. CONCLUSIONS: Polyurethane stenting without fluoroscopic guidance seems to be a valuable technique for primary management of nasolacrimal duct obstruction before dacryocystorhinostomy.     

正常泪道和泪道阻塞的CT检查

目的观察正常泪囊和鼻泪管以及泪道阻塞的CT表现。方法对32例正常泪道CT片及19例泪道阻塞患者CT表现进行观察分析。结果对正常泪道轴位软组织窗CT扫描图像进行分析:泪囊78.1%显影、21.9%不显影,鼻泪管均可显示;显影的泪囊和鼻泪管可分为双侧含气影、双侧黏膜影、一侧含气一侧黏膜影。4例泪道占位病变CT显示:泪囊区高密度影,鼻泪管扩张增粗,管内组织高密度。9例外伤后泪道阻塞CT显示:泪囊区软组织增厚,泪囊扩张或密度增高,泪囊区异常骨碎片影,鼻泪管骨折和阻塞。6例泪囊和鼻泪管炎症CT表现:泪囊区软组织增厚、密度增高,鼻泪管阻塞和密度增高。结论对正常泪道软组织窗轴位进行CT扫描:泪囊可显影或不显影;鼻泪管均可显影;显影的泪囊和鼻泪管表现为含气影或黏膜密度影。泪道占位、外伤和炎症均可在CT片上明确显示,利于诊断。     

Unsuccessful Probing and Nasolacrimal Canal Agenesis in Congenital Epiphora

Purpose: To present 3 cases with nasolacrimal canal agenesis who underwent repetitive unsuccessful probing for treatment of congenital epiphora.

Materials and methods: Three patients who had undergone topical antibiotic therapy, lacrimal sac massage and repetitive probing in Ondokuz Mayis University, Medical School, Ophthalmology Department between June 2006 and March 2007 were included in the study. Thin-section computerized tomography (CT) scan was performed in all cases since nasolacrimal duct could not be detected during repetitive probing.

Results: Among the patients 2 were males and 1 was a female. They were within the age range 5–7. Since it was not possible to cannulate the nasolacrimal canal during probing, CT scans were performed and nasolacrimal duct agenesis was detected in 3 patients. One of the patients had additional upper punctum agenesis, who also had no right frontal sinus and left sphenoid sinus. All tomographic images revealed a rudimentary upper nasolacrimal canal ending blindly and a lower canal leading into the maxillary sinus, which was very typical for the duct agenesis. In all patients, lacrimal fossas were shallow and irregular.

Conclusion: Nasolacrimal duct agenesis should be considered in patients with congenital nasolacrimal duct obstruction and unsuccessful repetitive probing, especially if it is difficult to cannulate nasolacrimal canal during probing. Although assessing whether dacryocystorhinostomy is in favor of the patient, the lacrimal sac and fossa should be examined with imaging in details.