Evaluation of nasolacrimal canal morphology in different facial skeletal relationships

BACKGROUND

Abnormal morphological variations of nasolacrimal canal (NLC) and its lack of understanding contributes to acquired injuries during craniomaxillofacial surgical procedures which leads untoward postoperative complications like nasolacrimal obstruction (NLO) and epiphora.

PURPOSE

The purpose of this study was to determine dimensional and volumetric morphological variations of nasolacrimal canal in various facial skeletal relationships which aid in performing a precise and safe surgery.

MATERIALS AND METHODS

This retrospective cohort study involved dimensional and volumetric analysis of nasolacrimal canal procured from computed tomography scans of 47 individuals grouped as ClassI, Class II and Class III, and unilateral cleft lip and palate (UCLP) groups. The outcome variables included length of NLC, volume of NLC, distance between the inferior orifice of the NLC to nasal floor, distance between inferior orifice of NLC to canine apex and distance between inferior orifice of NLC to central incisor apex. The objectives were to analyse morphological variation of NLC in different facial skeletal relationships and to evaluate the variation with change in facial sides and its relationship with surrounding structures.

RESULTS

Volume of the NLC was found significant in Class I and UCLP population (p < 0.05) with the greatest volume in the UCLP group. The mean linear and volumetric measurements between the right and left sides were found insignificant among all groups. Inferior orifice of NLC from canine apex were farthest in Class III and nearest in the UCLP group (p < 0.05). There was no significant association between outcome variables and skeletal base configuration.

CONCLUSION

NLC demonstrates dimensional and anthropometric variations between different skeletal relationships and this study is inevitable in understanding the probability of NLC injury during maxillofacial surgeries.

Morphometric and morphological evaluation of the nasolacrimal groove in 150 dry bones in the Anatolian population

PUPOSE

In this study, we aimed to evaluate the anatomical features of the nasolacrimal groove in detail by providing a morphological classification based on morphometric evaluations of the nasolacrimal groove.

METHODS

A total of 150 sagittal dry bones in the Department of Anatomy, Faculty of Medicine, Istanbul University were evaluated. The length and the width at different points of the nasolacrimal canal were calculated. According to the widths of the nasolacrimal canal ten different morphological types were revealed.

RESULTS

The length of the canal was found as mean 13.62 ± 2.42 mm on the right and 12.44 ± 2.68 mm on the left side. The entrance, the base, the upper and the lower thirds of nasolacrimal canal were 6.22 ± 1.19 mm, 7.95 ± 1.85 mm, 5.85 ± 1.06 mm, 6.60 ± 1.54 mm, on the right and 6.08 ± 1.16 mm, 7.24 ± 1.64 mm, 5.45 ± 1.29 mm, 6.23 ± 1.48 mm, on the left side, respectively. The width of the entrance of the nasolacrimal canal was the narrowest width compared to the base, upper and lower thirds in 7/10 types of 71/150 cranial bones.

CONCLUSION

This comprehensive morphological classification of the nasolacrimal groove sheds new light on its complex variations. We support that the finding of this study has the potential to improve the precision of diagnostic assessments and guide specific therapeutic interventions for patients with lacrimal drainage disorders.

[Anatomical structure and morphometric parameters of the distal segment of the lacrimal drainage system]

The article analyzes the literature data concerning the anatomical structure of the tear ducts with a focus on morphometric studies of individual structures. It is noted that, despite the high information content of cadaveric studies, most of the information to date has been obtained with the use of intravital radiation visualization methods. It is shown that the lacrimal drainage system has age, gender, and racial characteristics. Most studies focus on features of the bone nasolacrimal canal, while there is a relative shortage of research devoted to soft-tissue nasolacrimal duct. The analysis showed that most of the studies are devoted to particular morphometric indicators, which makes it difficult to obtain a complete objective picture of the size of the tear duct. Information about its volume can be found only in a couple of studies. The numerical values of the obtained data vary, which can be explained by a different approach to the selection of research subjects, sample sizes, anatomical criteria and the calculation method of morphometric parameters. There are only a few studies on morphometric parameters of the nasolacrimal duct in healthy humans, which is extremely important for determining the pathogenesis of disorders of the patency of the lacrimal drainage system.

Endoscopic "retrograde" dacryocystorhinostomy: A fast route to the lacrimal sac

Endoscopic Dacryocystorhinostomy (DCR) is an established surgical technique for the management of peripheral nasolacrimal duct (NLD) obstruction. Its main points are the correct identification of the lacrimal sac and the execution of surgical procedures that allow a rapid and accurate healing of the surgical field. The main endoscopic landmarks used for the identification of the lacrimal sac are the middle turbinate and the maxillary line. However, in some cases, this procedure can be difficult due to several factors (e.g. anatomical variations, former surgery). In the present study, a variation of "classic" endoscopic DCR, named "retrograde" endoscopic endonasal DCR (rDCR), is described. rDCR is performed through the quick identification of the NLD at the level of the most anterior insertion of the inferior turbinate in the lateral nasal wall. In most cases, at this level only a very thin shell of bone is present (crack point), easily fractured by using blunt angled dissector. The duct is then followed upward along its course by removing the overlying bone in order to correctly identify the lacrimal sac and unequivocally drill along the lacrimal pathway. This technique proved to be a safe, quick and effective procedure, even in patients with difficult anatomy.

Endoscopıc Anatomy of the Lacrımal Sac: A Cadaverıc Study

OBJECTIVE

To describe the anatomy of the lacrimal sac in relation to the lateral nasal wall by cadaver dissection, and to measure the distances of surgically important landmarks from relevant structures for safer and more efficient surgery.

METHOD

A total of 12 endoscopic dacryocystorhinostomy (DCR) were performed on both sides (right and left) of 6 fresh-frozen cadavers. The distances of the lacrimal sac to the posterior edge of the uncinate process, the frontal process of the maxilla, the maxillary ostium, the nasal vestibule, the middle turbinate attachment and the inferior turbinate were measured. In addition, the width and length of the lacrimal sac were measured.

RESULTS

The mean width and length of the lacrimal sac were 5.6 mm and 11.1 mm, respectively. The lacrimal sac was located at 15.2 mm from the posterior edge of the uncinate process, at 35.5 mm from the nasal vestibule, at 13.5 mm from the maxillary ostium, at 12.2 mm from the frontal process of the maxilla, at 8.7 mm from the middle turbinate attachment, and at 7.3 mm from the inferior turbinate.

CONCLUSION

This study provides additional measurements regarding the lacrimal sac and its relationships with nearby landmarks for use in endoscopic dacryocystorhinostomy. The distances of the lacrimal sac to the nasal vestibule, the uncinate process and the frontal process of the maxilla are not as reliable as the middle turbinate attachment for predicting the anatomic localization of the lacrimal sac during DCR.

Morphometric differences in normal bony nasolacrimal anatomy: comparison between four ethnic groups

PURPOSE

To compare bony nasolacrimal duct anatomy between ethnic groups.

METHODS

A retrospective observational study of patients of four ethnic groups who had high-resolution CTs between 2004 and 2019 covering the full length of their nasolacrimal ducts in two hospitals in Essex, England. Only normal ducts were included; patients with tearing or radiological abnormalities were excluded. Measurements were taken of the nasolacrimal duct and surrounding anatomy based on measurements found in the existing literature.

RESULTS

More females (n = 114) than males (n = 40) were included. South Asian (Indian subcontinent), Afro-Caribbean and European groups were equivocal demographically (n = 25-29, mean age 40-45); however, the Oriental group was fewer in number (n = 13) and slightly older (mean age 51). South Asian and European ducts had no significant differences. Afro-Caribbean ducts were wider and shorter than European. Afro-Caribbean faces are wider and their noses flatter and wider than European. Oriental ducts were wider and longer than European, but Europeans have taller noses.

CONCLUSION

The results from our Oriental group fits with the published data in Orientals. The bony nasolacrimal duct is greater in calibre (inner diameter) if the patient is of Afro-Caribbean or Oriental origin compared to European or South Asian. Acquired nasolacrimal duct obstruction in Afro-Caribbean or Oriental patients may be more likely due to secondary causes.

Extraoral anatomy in CBCT – a literature review. Part 1: Nasoethmoidal region

Cone beam computed tomography has become a widely used imaging technique for dental indications. Depending on the selected size of the field of view, anatomical structures outside the dentomaxillary complex become visible. As a consequence, the clinician must be able to interpret also those anatomical regions. In this article, the anatomy of the nasoethmoidal region is presented based on a literature review. The nose is characterized by the nasal septum and the superior, middle, and inferior conchae. The turbinates may be pneumatized (concha bullosa), mainly the middle concha. The ethmoid bone has a complex morphology (ethmoid labyrinths) and contributes with its perpendicular plate to the nasal septum. Other structures of the septum include the vomer and the septal cartilage. The nasal meatuses stabilize the airflow and direct the inhaled air to the nasopharynx via the choanae. The middle nasal meatus, which is also a part of the so called ostiomeatal complex, serves as the major drainage area (semilunar hiatus) of the paranasal sinuses, i.e., maxillary sinus, anterior ethmoid cells, and frontal sinus. Posterior ethmoid cells empty into the superior meatus and the sphenoid sinus drains into the sphenoethmoidal recess, located above the superior concha. The nasolacrimal duct that is running along the middle portion of the lateral nasal wall opens into the inferior nasal meatus.

Ocular Surface Disease of Rabbits

Rabbits have become a popular house pet that is encountered with increasing frequency in small animal veterinary practice. The unique anatomy of the rabbit predisposes them to developing surface ocular problems including the development of dacryocystitis, as well as conjunctivitis and keratitis. This article endeavors to give an updated outline of the various conditions affecting the rabbit ocular surface, with emphasis on diagnosis and treatment.

Endoscopic anatomy of the lacrimal sac for dacryocystorhinostomy. A cadaveric study

Objectives:

To assist the endoscopic localization of the lacrimal sac (LS) relative to nearby landmarks.

Methods:

This is a descriptive prospective anatomical study. Sixteen lateral nasal walls were dissected endoscopically to identify and localize the LS between October and November 2015. Multiple measurements were obtained from the NS to the anterior and posterior walls of the LS, as well as to the middle turbinate axilla (MTA) and from the MTA to the LS borders.

Results:

The average distance from the NS to the anterior border of the LS was 42.0 mm and the posterior border was 48.5 mm. The average widths of the LS were 7.55 mm superiorly, and 6.6 mm inferiorly representing a mathematical proof that the LS is a trapezoid shape. The mean distance from the NS to the MTA was 47.3 mm. Nine of the 16 lacrimal sacs (56.3%) were found to be partially overlapped by the MTA. The LS was only totally overlapped and lying posterior to the MTA in one side (6.3%), while in 6 sides (37.5%) the LS lay anterior to the MTA.

Conclusion:

Endoscopic surgeons should be aware of the location of the LS relative to nearby landmarks, particularly the MTA. Representing a mathematical proof that the LS is wider at it upper part than lower part best presented as a trapezoid shape. We have provided additional measurements that may prove useful in cases of difficult exposure.

Distal nasolacrimal duct showing the valve of Hasner

Recognition of the location of the nasolacrimal duct opening is important to prevent its damage while performing an intranasal inferior meatal antrostomy or creating a window transantrally in the inferior meatal wall during a Caldwell-Luc procedure.

Diagnostic imaging of the nasolacrimal drainage system. Part I. Radiological anatomy of lacrimal pathways. Physiology of tear secretion and tear outflow

Excessive watering of the eye is a common condition in ophthalmological practice. It may be the result of excessive production of tear fluid or obstruction and insufficiency of efferent tear pathways. The differentiation between obstruction and insufficiency of the lacrimal pathways is still clinically questionable. In the diagnostic process it is necessary to perform clinical tests and additional diagnostic imaging is often needed. Dacryocystography, with or without the extension of the dynamic phase or subtraction option, still remains the criterion standard for diagnostic imaging of the lacrimal obstruction. It may help to clarify the cause and exact place of the obstruction and provide information for further management, especially surgical treatment. Increasingly, new techniques are used in diagnostic imaging of the lacrimal tract, such as computed tomography, magnetic resonance, and isotopic methods. Adequate knowledge of the anatomy and physiology of the lacrimal system and the secretion and outflow of tears is the basis for proper diagnostic imaging. The purpose of this paper is to present the exact anatomy of the lacrimal system, with particular emphasis on the radiological anatomy and the current state of knowledge about the physiology of tear secretion and drainage.

[Preliminary study on features of three-dimensional ultrasound reconstruction of the lacrimal sac of normal adults]

OBJECTIVE

To measure and accumulate imaging anatomical data of lacrimal sac and medial canthal artery, and provide the knowledge for clinical diagnosis and therapy of lacrimal diseases.

METHODS

80 volunteers(80 eyes) who were eliminated the tearing related diseases by ophthalmologist were included. GE Voluson E8 ultrasound diagnostic apparatus with probe of high frequency 5-12 MHz was used, the probe of the three-dimensional ultrasound contacted eyes indirectly. The vertical diameter, anteroposterior diameter, width of lacrimal sac were measured, and vertical distance between top to bottom of lacrimal sac and medial canthus to skin, vertical distance between medial canthal artery and medial canthus to skin were also measured.

RESULTS

The measurement results of adult male subjects of lacrimal sac cavity vertical diameter and anteroposterior diameter and diameter were (13.3 ± 2.0) mm, (6.2 ± 1.1) mm, (5.0 ± 0.9) mm; the measurement results of adult female subjects of lacrimal sac cavity vertical diameter and anteroposterior diameter and diameter were (13.1 ± 2.2) mm, (5.8 ± 1.0) mm, (4.8 ± 0.8) mm, the difference was not statistically significant(t = 1.63, 1.45, 1.41, P > 0.05). The measurement results of adult male subjects of lacrimal sac cavity (top, bottom) to the top of the skin surface and medial canthal were (6.5 ± 0.1) mm, (5.9 ± 0.1) mm, (6.8 ± 0.1) mm, (8.8 ± 0.1) mm; the adult female group measurements were (6.1 ± 0.1) mm, (5.7 ± 0.1) mm, (6.2 ± 0.1) mm, (8.6 ± 0.1) mm, the difference was not statistically significant(t = 1.30, 1.56, 1.45, 1.63, P > 0.05). The measurement results of adult male subjects vertex are angular artery to the skin surface and medial canthal were (7.7 ± 0.1) mm, (8.0 ± 0.0) mm; the adult female group measurements respectively (7.6 ± 0.1) mm, (7.9 ± 0.1) mm, the difference was not statistically significant(t = 1.38, 1.34, P > 0.05).

CONCLUSIONS

Lacrimal sac and medial canthal artery can be showed clearly in three-dimensional ultrasound reconstruction, this can provide the guidance for clinical diagnosis and therapy of lacrimal diseases.

A cadaveric study of the morphometric relationships and bony composition of the caucasian nasolacrimal fossa

AIMS

To describe the morphometric relationships and bony composition of the nasolacrimal fossa in a Caucasian population with particular reference to the lacrimo-maxillary suture (LMS).

METHODS

Forty-seven orbits from 24 formalin fixed cadavers were exenterated. Morphometric measurements were taken between anatomical landmarks forming the lacrimal fossa on the medial orbital wall.

RESULTS

The mean recorded distance from the anterior lacrimal crest (ALC) to the posterior lacrimal crest (PLC) and the LMS were 8.8 mm (± 1.6) and 4.3 mm (± 1.1), respectively. In 25.5% of the orbits the LMS was at the mid-vertical line (MVL), defined as a line equidistant from the ALC and PLC. In 42.5% the LMS was located anterior to the MVL toward the ALC. In 66% of the orbits the LMS was at or within one standard deviation (SD) of the MVL. The LMS was >1 SD away from the MVL toward the ALC and PLC in 19% and 15% of orbits, respectively.

CONCLUSIONS

In a quarter of the orbits in our Caucasian population the nasolacrimal fossa was formed equally by the maxillary and lacrimal bones. However, in nearly a third of the cases the LMS was located closer to the PLC, indicating predominance of the thicker maxillary bone. This may result in greater difficulty in initiating the surgical osteotomy when performing a dacryocystorhinostomy. These data contribute to our understanding of the variation in lacrimal fossa anatomy and encourage further studies in different racial groups.

Developmental anatomy of the nasolacrimal duct: implications for congenital obstruction

OBJECTIVE

To measure the height, anteroposterior, and transverse diameters of the nasolacrimal duct (NLD) in normal children between 2 weeks and 34 months of age and to compare the development of the NLD with the maxilla.

DESIGN

Retrospective case series.

PARTICIPANTS

Thirty-eight children with no history of NLD abnormalities who underwent prior axial computed tomography (CT) facial scans of 0.50 to 0.625 mm resolution.

METHODS

Consecutive cases of CT facial series over a 16-month period at a single institution were studied.

MAIN OUTCOME MEASURES

Height, anteroposterior and transverse diameters, and volume of the NLD; height of the maxillary sinus.

RESULTS

The height of the bony NLD increases 1.8-fold, the average diameter increases 1.4-fold, and the volume increases 4.6-fold between 2 weeks and 34 months of age. The dimensional increases of the NLD are nonlinear, with most of the increase occurring in the first 6 months of life. The increase in height of the NLD is highly correlated with postnatal growth of the maxilla.

CONCLUSIONS

Spontaneous resolution of NLD obstruction in normal infants is coincident with elongation, limited radial extension, and the resulting volume expansion of the NLD. We propose that increases in hydrostatic pressure within the fluid column of the NLD combined with central cavitation of the epithelial core can account for the patency of the NLD in normal infants.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Morphology of the lacrimal sac and nasolacrimal duct in adult human cadaver

The lacrimal sac (LS) is a dilated structure that lies in the lacrimal fossa, and the nasolacrimal duct (NLD) is the continuation of LS from its neck up to the inferior meatus of the nose. A study of 50 specimens of formalin-fixed adult cadavers of both sexes of Indian origin was conducted. The morphological features like length and breadth of LS and NLD, along with the histology of LS has been observed. The mean length of LS and NLD on the right side was 10.5 mm (1.04) and 16 mm (2.6) respectively, whereas the mean breadth of the above structures, on the right side was 6 mm (0.63) and 5.66 mm (0.81) respectively. The mean length of LS and NLD on the left side was 10.57 mm (1.13) and 16.42 mm (2.29), whereas, the mean breadth of the same structure on the left side was 6.71 mm (0.95) and 5 mm (0.81) respectively. The sides did not show any significant statistical difference but when the correlation between the length and breadth of LS is considered, significance was observed in the lacrimal sac of the left side. No variations were observed in the gross structure of LS and NLD. Microscopic study showed the presence of elastic fibers in LS. The importance of LS and NLD is that the blockage of this lacrimal passage is the most common cause of epiphora (watering of the eye). The presence of elastic fibers in this study confirms the hypothesis that the sac elasticity may perform a dynamic role, in forceful evacuation of lacrimal fluid in reverse direction (Tab. 2, Fig. 3, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

Correlation between anthropometric facial features and characteristics of nasolacrimal drainage system in connection to false passage

BACKGROUND

To determine the correlation between the anthropometric facial features and the anatomy of the nasolacrimal drainage system.

METHODS

Forty-six mid-sagittal halves of 23 cadavers were studied. The inclination of the lacrimal sac (LS) and nasolacrimal duct (NLD), and the LS-NLD angle were measured in both the sagittal and coronal planes. For the facial features, the height, length and depth of the nose, the intercanthal distance, nasal breadth, nasofacial angle, distance between the external naris, and the inferior aperture of the NLD were measured. The correlations between the angles and the facial features were calculated.

RESULTS

The LS-NLD angle was classified into three anatomical types according to the inclination of the LS and the NLD in the sagittal and coronal planes; the anterior-inward type (43.5%), anterior-outward type (37.0%), and posterior-outward type (19.5%). The nasal depth was correlated with the sagittal LS-NLD angle, and the nasal height and length were correlated with the coronal LS-NLD angle.

CONCLUSIONS

There is a large variation in the LS-NLD angle, and nasal depth, height and length can be used to predict the direction of this angle.

Ontogeny of the nasolacrimal duct in primates: functional and phylogenetic implications

The ontogeny of the nasolacrimal ducts (NLD) and canals (NLC) are investigated in strepsirrhine and haplorhine primates. Developmental series of serially sectioned fetal, perinatal and adult specimens, in combination with juvenile and adult skulls subjected to high-resolution computed tomography, reveal that the vertical NLC and NLD of adult tarsiers and anthropoids are produced by the degeneration of a more horizontal anterior arm of the NLD that is present only transiently in haplorhines, but is maintained throughout life in strepsirrhines. This degeneration manifests as an 'unzipping' of the anterior arm by means of progressive enlargement (in a rostral direction) of a caudally placed opening of the NLD (at the base of the vertical NLC), followed by breakdown of the resulting epithelial groove. The similar mode by which the anterior arm of the membranous NLD degenerates in tarsiers and anthropoids strongly suggests that the conditions in these two taxa are homologous, and provides additional evidence for a monophyletic Haplorhini. The functional relationship between the nasolacrimal duct and the vomeronasal organ is reviewed in light of this evidence, and it is suggested that these changes in the haplorhine NLD were functionally linked to the development of anatomical haplorhinism of the oronasal complex.

[Endonasal anatomy of lacrimal sac and its clinical significance in dacryocystorhinostomy]

OBJECTIVE

To explore the intranasal surface localization of the lacrimal sac in endoscopic dacryocystorhinostomy.

METHODS

Fifteen adult cadavers (30 sides) were studied, the data of projection position of the lacrimal sac on the lateral wall of nasal cavity were measured.

RESULTS

In 2/3 cadavers, the lacrimal sac is located above the axilla of the middle turbinate, and 1/3 lies below it. A majority of the lacrimal sac (2/3) are located below the entry point of the common lacrimal canaliculus, about 1/3 lies above it. Inner canthal ligament projects on the middle of the lacrimal sac, almost equal to the level of common lacrimal canaliculus. Thirty-two cases (thirty-nine sides) of chronic dacryocystitis were followed-up > 6 months after operation. Thirty-five sides were cured, 2 sides improved and 2 sides ineffective. The cure rate was 89.8%, improve rate 5.1% and ineffective rate 5.1%, respectively, and the total effective rate was 94.9%.

CONCLUSIONS

The central position of dacryocystorhinostomy should be 0.2 cm above the front of the axilla of the middle turbinate, to make an curved mucous membrane incision 0.8 cm above and 0. 4 cm below the front of the axilla of the middle turbinate and bone ostium about 1.2 cm x 1.0 cm. It is the best position in endoscopic dacryocystorhinostomy. Locating the inner canthal ligament with a bayonet type forceps to find the projection of lacrimal sac is also a simple and easy method.

[The preliminary research of 3D-reconstruction of lacrimal sac under computer]

OBJECTIVE

To explore the application of 3D-reconstruction of lacrimal sac under computer.

METHOD

To the 3D model of lacrimal passage was reconstructed with CT scanning.

RESULT

The anatomy of lacrimal passage could be displayed with 3D-reconstruction under computer and the relation between lacrimal sac and the axilla of the middle turbinate could be observed and measured freely.

CONCLUSION

The technology of 3D-reconstruction under computer is greatly valuable in the anatomic research of lacrimal sac.

Nasolacrimal duct lavage in rabbits

Eye problems are common in both laboratory and pet rabbits. This column reviews the anatomy of the nasolacrimal duct system in rabbits and describes the appropriate techniques for working up a rabbit with an ocular problem related to nasolacrimal drainage.

Medial Microsurgical Approach to the Orbit: An Anatomic Study

The authors have identified and described three medial approaches to the intraorbital portion of the optic nerve in cadavers. The structures exposed via the superior, inferior or central approaches were approached through the medial orbital wall. The superior approach in which the medial rectus muscle is retracted inferiorly exposes the superomedial aspect of the orbit. The inferior approach in which the medial rectus muscle is retracted superiorly, provided the inferomedial aspect of the optic nerve from the globe to the muscle cone. The central approach in which the ethmoidectomy was performed and the medial rectus muscle was disinserted and retracted, provided excellent exposure of the structures of the medial part of the orbit and the optic nerve. There were no structures blocking access to the two third anterior optic nerve and medial surface of the globe. The structures encountered in these approaches are demonstrated under magnification in cadavers, and the exposure of the optic nerve is discussed.

[Endonasal anatomy of lacrimal sac to endoscopic transnasal dacryocystorhinostomy]

OBJECTIVE

To provide clinical guidance for the endoscopic transnasal dacryocystorhinostomy.

METHOD

Fifteen adult cadavers (30 sides) were studied on the projection anatomy of lacrimal sac on the lateral wall of nasal cavity and the relationship between lacrimal sac and inner canthal ligament were studied, too.

RESULT

A major portion of the sac (2/3) was located above the insertion anterior to the middle turbinate and, quite a part (1/3) of the sac lied above the entry point of the common canaliculus. Inner canthus ligament almost projected on the middle of the sac. The insertion of the front of the middle turbinate could pass the posterior facies (11 sides) even the long axis (1 side) of lacrimal sac. A localization method based on inner canthus ligament showed the degree of accuracy of 80%.

CONCLUSION

Dacryocyst iodized oil opacification CT scan should be performed. Surgical stoma location is about 1. 5-2. 0 mm above and slightly anterior to the insertion of the middle turbinate. A localization method based on inner canthus ligament shows a high accuracy. The common canaliculus entry point is comparatively permanent, a laser optical fiber should be used for lacrimal passages exploration on the surgery, and the light spot directed toward lacrimal bone on the nasal lateral wall is exactly as an identification marker.

Important anatomical landmarks in the lateral nasal wall

OBJECTIVE

The study aimed to investigate the anatomy of the lateral nasal wall to provide a set of measurements among some important anatomical landmarks and to reveal the relationship between them.

METHODS

Fifty half heads were dissected to determine the distances between important landmarks in the lateral nasal wall for endoscopic sinus surgery. Landmarks were measured with an electronic caliper. This study was carried out between December 2002 and February 2003 at the Anatomy Research Laboratory, Faculty of Medicine, Akdeniz University, Antalya, Turkey.

RESULTS

Results were provided as mean +/- standard deviation. In our study, some of the critical distances as in the lateral nasal wall were measured and results showed consistency to the data found in the literature.

CONCLUSION

Our results are useful to achieve safe endoscopic sinus surgery.

[Morphologic study of nasolacrimal duct mucosa-associated lymphoid tissue]

OBJECTIVE

To investigate the features of nasolacrimal duct MALT (mucosa-associated lymphoid tissue), and to explore the aetiology of chronic dacryocystitis.

METHOD

The mucous of nasolacrimal duct, nasal cavity, pharyngeal and trachea of 20 rabbits were studied, and the lymphoid tissue and HEV of them were compared.

RESULT

The number of lymphoid follicle and HEV in nasolacrimal duct epidermis were less than that in nasal cavity, pharyngeal and trachea (P<0.01).

CONCLUSION

In normal condition the immune response of nasolacrimal duct membranae is lower than other mucosa of head-neck.

[Morphometric characteristics and correlation interdependence of the lacrimal sac fossa and nasolacrimal canal in cerebral and facial parts of the skull of various shape]

Morphometric characteristics of lacrimal sac fossa (LSF) and nasolacrimal canal (NLC) were studied in 105 macerated skulls of humans of mature age. Extreme shape variants were detected for LSF and NLC inferior foramen. The peculiarities of topographic-anatomical relations of NLC with the neighboring structures of nasal cavity were established. Morphometric characteristics of LSF and NLC were found to be largely determined by the shapes of facial part of the skull, nasal cavity and orbit, and to a lesser extent by the shape of cerebral part of the skull. Some variants of LSF and NLC topographic-anatomical localization were found to exist that could predispose to spreading of an inflammatory process from the adjoining areas. Correlation analysis of morphogenetic relations of LSF and NLC has demonstrated significant dependence of only some dimensions in each of the skull shape variants.

The course of the nasolacrimal duct in brachycephalic cats

Casts of the nasolacrimal duct system were obtained from 50 euthanised cats including brachy-, meso- and dolichocephalic breeds. The course of the nasolacrimal duct, which was assessed radiographically and gross-anatomically, was strongly related to the shape of the skull. In meso- and dolichocephalic cats the nasolacrimal duct formed a dorsally opened arch with the descending part being directed rostroventrally. The main part of the duct passed the nasal cavity in a rather horizontal course parallel to the hard palate and was located ventrally to the lacrimal foramen. However, foreshortening of the face was associated with a right-angled or even acute-angled alignment of the duct. In higher degrees of brachycephaly the main part of the duct ascended beyond the level of the lacrimal foramen and passed the nasal cavity dorsal to the level of the lacrimal foramen. This specific course of the nasolacrimal duct in brachycephalic cats was consistent with a steeper alignment and attachment of the maxilloturbinate. Accessory orifices of the nasolacrimal duct opening into the nasal cavity had never been observed. The present results strongly suggest that the specific course of the nasolacrimal duct in brachycephalic cats might hinder the drainage of the lacrimal fluid irrespective of the diameter of the lumen of the nasolacrimal duct system.

The human nasolacrimal ducts

The human nasolacrimal ducts are a borderland of the disciplines ophthalmology and otorhinolaryngology, which work close together in the treatment of nasolacrimal disorders. However, little knowledge exists concerning the physiology of the nasolacrimal system and, therefore, its pathophysiology. The aim of the present investigations was to obtain a better understanding of tear flow physiology, microbial defence strategies and pathophysiological processes by analysing the nasolacrimal system, thus opening new perspectives against existing therapeutical concepts of diseases of the nasolacrimal ducts. The human nasolacrimal ducts consist of the upper and the lower lacrimal canaliculus, the lacrimal sac and the nasolacrimal duct. They drain the tear fluid from the ocular surface into the lower meatus of the nose. The lining epithelium of the lacrimal sac and the nasolacrimal duct is faced by microvilli, and animal experiments in rabbits support the hypothesis that tear fluid components are absorbed in the human nasolacrimal system. Evidence of seromucous glands, intraepithelial lipids and a specific mucus layer leads to the conclusion that the normal three-layering of the tear film is also present in the nasolacrimal ducts. Based on its composition, the mucus layer, which is mainly synthesised by goblet cells and intraepithelial mucus glands, functionally serves as a simplified drainage of tear fluid, and it is attributed similar properties to epithelia of the gastrointestinal tract. Further defence mechanisms are represented by antimicrobial peptides IgA and immunocompetent cells (lymphocytes and macrophages) which show intraepithelially and subepithelially a special distribution. Moreover, organised lymphoid tissue is present, which reveals the cytomorphologic and immunophenotypic characteristics of mucosa-associated lymphoid tissue. The wall of the lacrimal sac and the nasolacrimal duct are made up of a helical system of different connective tissue fibres. Wide luminal vascular plexus are embedded in this helical system, which is comparable to a cavernous body. Caudally, the vascular system is connected to the cavernous body of the inferior turbinate. With distension the system may be "wrung out" due to its medial attachment and helically arranged fibrillar structures. Thereby, tear fluid is drained distally. The embedded blood vessels underlie vegetative control. By means of this innervation, the specialised blood vessels permit regulation of blood flow by opening and closing the lumen of the lacrimal passage as effected by the engorgement and subsidence of the cavernous body, at the same time regulating tear outflow. Related functions, such as a role in the occurrence of epiphora related to emotional responses, are relevant. Moreover, malfunctions in the cavernous body and in its innervation may lead to disturbances in the tear outflow cycle, ocular congestion or total occlusion of the lacrimal passage. Thus, the pathophysiology of primary acquired dacryostenosis can be explained: Descending inflammation from the eye or ascending inflammation from the nose initiates swelling of the mucous membrane, remodelling of the helical arrangement of connective tissue fibres, malfunctions in the subepithelial cavernous body with reactive hyperaemia, and temporary occlusion of the lacrimal passage. In the follow-up, repeated isolated occurrence of dacryocystitis leads to structural epithelial and sub-epithelial changes, which may lead either to a total fibrous closure of the lumen of the efferent tear duct or to a non-functional segment in the lacrimal passage that is manifest on syringing. 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 autoimmunologic response that could cause dry eye pathology.

Incorrect medical terms in terminologia anatomica

We suggest changing the incorrect term of "sinus venosus sclerae" to the exact and logical term of "sinus aquosus sclerae" since this sinus does not contain venous blood, but humor aquosus. We further suggest the name changing "ductus nasolacrimalis" to "ductus lacrimonasalis" signifying thus the exact direction of the flow of the tears.

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.

Fusiform enlargement of the nasolacrimal canal: a rare anatomic variation

To determine the standard width and shape of the nasolacrimal canal (NLC) in the coronal plane, a retrospective review of 950 coronal paranasal CT sections was undertaken. The coronal diameter of NLC was measured at its upper and lower ends and anomalies in its configuration noted. The mean diameters of the NLC were 4.8 +/- 1.2 mm and 4.7 +/- 1.1 mm on the right and left sides, respectively. There was no difference in the mean NLC diameter between the right and left sides, upper and lower portions or males and females. In two cases, an abnormal dilation of the NLC at its inferior portion was encountered. A marked enlargement of the NLC can occur in the absence of a neoplastic or obstructive process and may be detected as an isolated finding representing idiopathic or congenital enlargement. Segmental NLC dilatation is not always an indicator of pathology, particularly in asymptomatic cases, and should be considered a rare anatomic variation.

Gross and microscopic anatomy of the extraorbital lacrimal gland of the common marmoset (Callithrix jacchus)

PURPOSE

The lacrimal gland is often selected for microscopic examination in toxicologic studies. However, this gland is difficult to find within the orbit in marmosets at necropsy. Therefore, we examined the extraorbital lacrimal glands in marmosets.

METHODS

The formalin-fixed craniums of four marmosets were used in a topographic study to confirm location of the lacrimal gland, and the results were applied to a routine toxicologic study in marmosets.

RESULTS

The extraorbital lacrimal gland was located on the temporal surface of the zygomaticofrontal process and was covered with the temporalis muscle. The gland was easily detached from the surrounding tissue, and its histologic features were the same as those of the intraorbital lacrimal gland.

CONCLUSIONS

The extraorbital lacrimal glands have been reported in some New World monkeys, but to the authors' knowledge, this is the first report in marmosets. Identification and characterization of this gland will be useful for toxicologic studies in marmosets.

Frequency of the common canaliculus: a radiological study

BACKGROUND

It is frequently stated in the literature that there is a common canaliculus (CC) in the lacrimal drainage system in about 90% of individuals; in the remaining 10%, the upper and lower canaliculi enter the lacrimal sac separately. To our knowledge, there is no quantitative study supporting this assumption.

OBJECTIVE

To investigate the frequency of the CC and other anatomical types connecting the upper and lower canaliculi to the lacrimal sac.

MATERIALS AND METHODS

We presumed that there might be 3 different types of anatomical connection between the lacrimal sac and the canaliculi. Digital subtraction macrodacryocystograms obtained from 281 patients with obstructive epiphora were reviewed, and those of 247 patients were included in the study. These patients were grouped according to the anatomical types.

RESULTS

Dacryocystographies were performed on 153 patients unilaterally and 94 bilaterally. We observed a CC in 321 (94.1%) of 341 lacrimal drainage systems. In 13 lacrimal drainage systems (3.8%), the CC was absent, but the upper and lower canaliculi joined at the wall of the lacrimal sac. In only 7 lacrimal drainage systems (2.0%) did the upper and lower canaliculi enter the sac separately. In 2 patients with bilateral dacryocystograms, a CC was seen on one side but not on the other side.

CONCLUSIONS

The frequency of separate drainage of the upper and lower canaliculi into the lacrimal sac is only 2.0%. The CC might not be present bilaterally in all individuals.

Intranasal anatomy of the nasolacrimal sac in endoscopic dacryocystorhinostomy

Intranasal surface anatomy is fundamental to the technique of endoscopic dacryocystorhinostomy. In the current literature the lacrimal sac is described as being situated anterior to the anterior end of the middle turbinate with between 0% and 20% of the sac above the insertion of the middle turbinate on the lateral nasal wall (the axilla of the middle turbinate). The aim of this study was to use CT dacryocystograms (DCGs) and CT scans to establish the relationship of the lacrimal sac to the lateral nasal wall. Forty-seven individual lacrimal sacs were measured in relation to the common canaliculus, and 76 were measured in relation to the insertion of the middle turbinate. Measurements taken from the long axis of the sac showed the mean height of the sac above the middle turbinate insertion was 8.8 mm (SD = 0.2, 95% CI = 1.3) and below it was 4.1 mm (SD = 2.3, 95% CI = 1.1). The average measurement of the sac above the com-mon canaliculus on CT DCGs was 5.3 mm (SD = 1.7, 95% CI = 0.56), whereas the average measurement below the common canaliculus was 7.7 mm (SD = 2, 95% CI = 1.3) (n = 47 CT DCGs). The findings in this study show that a major portion of the sac is locat-ed above the insertion of the anterior end of the middle turbinate and, in addition, that a significant part of the sac lies above the entry point of the common canaliculus. Knowledge of these findings can ensure that the sac is adequately exposed during dacryocystorhinostomy by removal of sufficient bone and mucosa above the anterior insertion of the middle turbinate.

Septomaxilla of nonmammalian synapsids: soft-tissue correlates and a new functional interpretation. DELETE

The function of the septomaxilla of nonmammalian synapsids has long been problematic. Distinctive features of this bone, including a prominent intranarial process and a septomaxillary canal and foramen, are characteristic of pelycosaurs and nonmammalian therapsids, but are lost in their mammalian descendants. Numerous contradictory reconstructions have been proposed for the soft anatomy associated with the septomaxilla of nonmammalian synapsids. This review supports the following conclusions: 1) No particular correlation exists between the septomaxilla and the vomeronasal organ (VNO), and the most likely location for the VNO is on the dorsal surface of the palatal process of the vomer; 2) The most likely occupant of the septomaxillary canal is the nasolacrimal duct, which opened either anterior or medial to the intranarial process, near the opening of the VNO duct; and 3) The occupant of the septomaxillary foramen remains uncertain. These conclusions suggest that the functional significance of the septomaxilla in the nonmammalian synapsids is tied to that of the nasolacrimal duct. The association of this duct and the VNO in these animals resembles the condition in Recent amphibians and lepidosaurs, in which the nasolacrimal duct supplies orbital fluids to the VNO, apparently to enhance vomeronasal function. The peculiar shape of the synapsid septomaxilla may have served to collect vomeronasal odor molecules. The changes of the septomaxilla in early mammals, and its nearly complete loss in extant mammals, are probably correlated with a dissociation of the nasolacrimal duct and VNO, and functional changes in both structures.

[Micro-endoscopy of the lacrimal apparatus combined with Erbium YAG laser: an anatomical study. New methods of imaging]

PURPOSE

To study the anatomic structure and the endoscopic aspect of the lacrimal drainage system and to evaluate the efficacy of the Erbium laser with microendoscope in lacrimal obstruction.

METHODS

Twenty lacrimal ducts from ten fresh cadaver heads were used to lead a special rigid probe of 1.1. mm diameter (Endognost Schwind). This probe combined a flexible endoscopic probe of 500 mu, an Erbium laser fiber of 375 mu and an irrigation. The probe was introduced through the inferior canaliculus. Progressing in the lacrimal system, all the images were analysed. Then, we used the laser fiber to open the lacrimal sac mucosa and the lacrimal bone.

RESULTS

The anatomo-endoscopic analysis was performed using endoscopic data. We appreciated essentially the walls of valves and sinuses that appeared only functional when increasing the irrigation flow. The laser could easily open the mucosa and the lacrimal bone but not the maxilla.

DISCUSSION

The small size of the cannula allows to use the system for the diagnosis of lacrimal obstructions. The combined laser allows to treat at same time canalicular obstructions and lower obstructions.

CONCLUSION

The endocanalicular study of the lacrimal drainage system can diagnose the type of obstruction and can treat it. A clinical study is requested to confirm these results.

[The applied anatomy and measure of nasolacrimal duct]

OBJECTIVE

To know the anatomy of nasolacrimal duct.

METHOD

80 half-skulls of chinese adult were used to observe shapes of the orifice.

RESULT

Five shapes of the orifice were found. Slit-shape was the most in all shapes. 73 nasolacrimal ducts and situation of orifices have been measured with results as follows: (1) The nasolacrimal duct length is 14.14 mm (mean value); (2) The distance from the inferior margin of the anterior nostril to the anterior margin of the orifice (D.N.O.) is 29.00 mm (mean value); (3) The distance from the anterior attachment of the inferior turbinate to the anterior margin of the orifice is 11.70 mm (mean value); (4) The distance from the inferior margin of the anterior nostril to the anterior attachment of the inferior turbinate (D.N.T) is 18.30 mm (mean value). With analysis of linear regression, the relationship between the "D.N.T." and the nasolacrimal duct length, the "D.N.T." and the "D.N.O." is positive linear correlation respectively, "D.N.T." has been able to be measured easily, so the nasolacrimal duct length and the situation of the orifice have been recognized.

CONCLUSION

D.N.T. may be used in clinical teaching and researching work.

[Basic study of MR-dacryocystography]

We developed MR-dacryocystography as a non-invasive, safer imaging technique for canaliculi, the nasolacrimal duct and lacrimal sac by dropping saline solution and diluted Gd-DTPA solution into the eye. The diluted Gd-DTPA solution was found to create no local irritation in the eyes of rabbits and normal volunteers. Lacrimal sacs and ducts were well visualized in all of 10 normal volunteers by using the saline solution or the diluted Gd-DTPA solution. Canaliculi were visualized in 4-7 cases on thin-slice axial images. MR-dacryocystography was suggested to be a useful screening examination for lacrimal outflow disorders.

[Anatomical consideration for the injury of dacryocyst and nasolacrimal duct during intranasal sinus surgery]

Based on dissection and measurement on 20 adult head cadavers, there is the close relationship between lacrimal duct and lateral wall of the nasal cavity. The cells of anterior ethmoid sinus were classified into three degrees, according to the relationship between the anterior ethmoid sinus and the lacrimal sac fossa. The average distance is 6.74 +/- 1.72 mm between the nasolacrimal duct and the upper part of the uncinate process, 3.44 +/- 0.75 mm and 5.50 +/- 3.73 mm from the nasolacrimal duct to ethmoidal infundibulum and the maxillary ostium. The orifice of the duct most commonly opens under the insertion of the inferior turbinate anteriorly. To perform intranasal sinus surgery, the safest area and key operation approach were discussed.

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.

CT-anatomy of the nasolacrimal sac and duct

Recent developments in ophthalmology such as balloon dilatation, stent implantation, laser therapy and endoscopy of the lacrimal drainage system raise the need for a detailed anatomical knowledge of this system. In this study morphometric measurements of the lacrimal drainage system were performed with thin-section axial computed tomography (CT) examinations in 147 patients with no signs of pathology related to the lacrimal drainage system. The mean length of the nasolacrimal duct measured 11.2 +/- 2.6 mm (range: 6-21 mm), the narrowest diameter was 3.7 +/- 0.7 mm (range: 2-7 mm). The mean length of the nasolacrimal sac was 11.8 +/- 2.5 mm (range: 6-18 mm). The width of the nasolacrimal sac did not exceed 4 mm unless filled with air. In 43 (29.3%) of the subjects air was visible within the nasolacrimal sac or duct. The knowledge of the morphometry of the lacrimal drainage system enables the ophthalmologist to plan intervention on the lacrimal drainage system precisely and avoid unnecessary manipulations.

An anatomical basis for primary acquired nasolacrimal duct obstruction

OBJECTIVE

To measure any sex size differences in the bony nasolacrimal drainage systems in a normal, age-matched population.

METHODS

A retrospective study of axial cut maxillofacial computed tomographic scans was conducted. Three levels of the bony nasolacrimal duct (NLD) system on the right and left sides were measured along the anteroposterior diameter. The data were analyzed using 2-tail t test, analysis of variance, and linear regression methods.

RESULTS

Scans from 71 adult patients (36 men and 35 women) were reviewed. Women were found to have a smaller bony diameter at the level of the lower fossa (P = .01) and the middle NLD (P = .06) compared with those of men. The adult inferior bony fossa increased in size with age in both men and women, while the middle NLD increased in size in men only. No significant size difference was found between the right and left side at any level.

CONCLUSIONS

Size differences are found in measurements of bony nasolacrimal excretory systems in men vs women. Women have significantly smaller dimensions in the lower nasolacrimal fossa and the middle NLD. The anteroposterior dimension of the bony nasolacrimal canal at the fossa level enlarged in both sexes, with age co-inciding with osteoporotic changes throughout the body. These quantitative anatomical observations provide a contributory factor to explain the increased prevalence of primary acquired NLD obstruction in women.

Microbiologic, radiographic, and anatomic study of the nasolacrimal duct apparatus in the rabbit (Oryctolagus cuniculus)

This study was motivated by the sporadic observation of epiphora in two male rabbits. The epiphora was unilateral and not associated with conjunctivitis or Pasteurella infection. To characterize the cause of epiphora, we studied 15 specific-pathogen-free New Zealand White rabbits. This study group was composed of the two affected males, four unaffected males, and nine unaffected females. Clinical evaluation consisted of bacterial culture of conjunctival specimens, examination of conjunctival scrapings for chlamydial inclusions, culture and cytologic examination of specimens from the nasolacrimal duct, plain and contrast radiography, latex casting, histologic examination, and the Schirmer tear test. Important differences found in the rabbits with epiphora included an opalescent, gritty, nasolacrimal duct flush fluid and marked unilateral dilatation of the duct proximal to a dorsal flexure at the caudal limit of the incisor tooth root. The flush solution from one affected rabbit cleared with ether, suggesting the presence of triglycerides or cholesterol. The organisms most commonly isolated from the conjunctiva were Moraxella sp., Oligella urethralis, Staphylococcus aureus, coagulase-negative Staphylococcus sp., and Streptococcus viridans. The organisms most commonly isolated from the nasolacrimal duct flush fluid were Moraxella sp., S. viridans, and Neisseria sp. Culture of the nasolacrimal duct flush fluid yielded microorganisms more consistently than did culture of the conjunctival specimens. All microorganisms isolated from affected rabbits also were isolated from unaffected rabbits. There was no apparent contribution of microorganisms to the development of epiphora, and Schirmer tear test results for affected animals were within the range seen in unaffected animals. Occlusion of the nasolacrimal duct was presumed to be attributable to fat droplets. This study augments the existing literature and represents the first report of anomalous nasolacrimal duct anatomic features in the rabbit.

The anatomy of the common canaliculus

BACKGROUND

The functional valve between the common canaliculus and the lacrimal sac has traditionally been attributed to the valve of Rosenmüller, although this anatomical structure has never been rigorously documented.

OBJECTIVE

To define the anatomy of the canaliculus-sac junction.

METHODS

Twelve rigid plastic casts of the lacrimal outflow systems were obtained in human cadaver specimens using a well-known biologic casting material (partially polkymerized monomer to which a catalyst and promoter were added).

RESULTS

A consistent pattern of angulation within the canalicular system was documented. The canaliculi bend posteriorly behind the medial canthal tendon, then anteriorly to enter the sac at an acute mean angle of 58 degrees to the lateral wall of the sac.

CONCLUSIONS

This consistent configuration at the canaliculus-sac junction has not been previously described and may contribute to the 1-way valve phenomenon seen in some lacrimal disorders.

Intranasal visualization for nasolacrimal duct intubation

PURPOSE/METHODS

To improve intranasal visualization of nasolacrimal procedures we use a self-retaining nasal speculum with or without a sinuscope.

RESULTS/CONCLUSIONS

Placement and retrieval of silicone stents can be accomplished with less trauma than with a blind sweep technique. Additionally, the valve of Hasner can be seen and the creation of false passages avoided.

[Comparison of anatomy and imaging of the orbital area and the nasolacrimal duct]

The orbit and its appendages were analysed on anatomical sections, CT scans and magnetic resonance imaging in order to define the various constituents of the orbitonasolacrimal apparatus in the various planes. The series of sections presented should enable surgeons to define the landmarks in this region, especially in the approach to deep structures.

Gadolinium magnetic resonance imaging dacryocystography

A 1:100 solution of 48% gadopentolate in liquid tear solution was used in magnetic resonance dacryocystography to image the canaliculi, nasolacrimal sac, and nasolacrimal duct. It was administered as an eyedrop, one drop every minute for five minutes, immediately before scanning in six normal and five abnormal nasolacrimal outflow systems. In cases of nasolacrimal obstruction, the dilute gadolinium solution was injected through the canaliculus immediately before scanning. A three-inch surface coil enhanced the detail of soft-tissue structures such as the canaliculi and lacrimal sac. In the evaluation of complex tearing disorders such as congenital, neoplastic, postsurgical, and posttraumatic nasolacrimal obstruction, gadolinium lacrimal contrast adds useful information to magnetic resonance images of the lacrimal outflow system. Because of the expense of the test, we do not recommend it as a routine examination.