Anatomical and morphometric study of the bony nasolacrimal canal using computed tomography

CT-Measured Angulation Between the Frontal Bone and Bony Nasolacrimal Duct: Variations in Obstructed and Healthy Lacrimal Ducts

PURPOSE

The aim of this study was to analyze the characteristics of CT-measured intersection angle (FB-BNLD) between the frontal bone and bony nasolacrimal duct and to provide suggestions for treating primary acquired nasolacrimal duct obstruction (PANDO) patients in West China.

METHODS

Three hundred and nine participants' CT were, respectively, evaluated with RadiAnt DICOM Viewer. We defined the FB-BNLD angle >0° as the anterior type and the FB-BNLD angle ≤0° as the posterior type.

RESULTS

The mean FB-BNLD was -2.52° (95% CI, -3.16° to -1.88°) across all participants, of whom 37.2% were of the anterior type and 62.8% of the posterior type. Approximately 65.0% of the female patients had a posterior FB-BNLD type, and 54.2% of the male patients had an anterior FB-BNLD type (p = .002). Posterior FB-BNLD was the dominant type in the PANDO and control groups (p = .011), and the angle of FB-BNLD was statistically different in both groups (PANDO group, -2.54° to -0.71°; control group, -4.42° to -2.67°; p < .001). Among the male participants, the type of FB-BNLD differed between the two groups (p = .036), with differences in the angle of FB-BNLD (PANDO group, 0.59° to 5.13°; control group, -4.08° to 1.89°; p = .034). There was no difference in the type of FB-BNLD in female participants between the two groups (p = .051).

CONCLUSION

The present study revealed individual differences in the type of FB-BNLD, with anterior-type majority in males and posterior-type dominance in females. Evaluating the FB-BNLD type on CT can provide a fast method for knowing the nasolacrimal duct condition during planning for lacrimal manipulation.

Comparing the diagnostic accuracy of MR dacryocystography (MRD) and dacryoscintigraphy (DSG) in NLDO-related acquired epiphora

PROPOSE

This study aimed to compare the diagnostic accuracy of MR dacryocystography (MRD) and dacryoscintigraphy (DSG) in the diagnosis of acquired epiphora related to NLDO. A total of 15 patients with acquired epiphora and suspected NLDO were included in this study.

METHODS

All patients underwent MRD and DSG examinations. MRD was performed using a 3-Tesla magnetic resonance imaging (MRI) scanner, while DSG involved injection of a radiotracer into the lacrimal drainage system followed by DSG. The results of both imaging methods were compared with the reference standard that was a combination of clinical examination findings and surgical exploration.

RESULTS

The results of this study showed that no abnormal findings were observed in MR-DCG in patients before the Valsalva maneuver. However, after the Valsalva maneuver, stenosis/obstruction at the canal surface was observed in all 15 patients diagnosed by DSG, giving a sensitivity of 100% for canal stenosis. Moreover, the results revealed that among these 15 patients, 9 showed stenosis or simultaneous obstruction at the level of the canal and lacrimal sac, but MR-DCG showed these lesions in only 9 patients, giving a sensitivity of 60%. The specificity of MRD and DSG were 85% and 76.7%, respectively. There was a statistically significant difference in the sensitivity of MRD and DSG (p < 0.05).

CONCLUSION

This study demonstrated that MRD has a higher diagnostic accuracy in the diagnosis of acquired epiphora associated with NLDO compared to DSG. MRD showed significantly higher sensitivity and specificity than DSG. Therefore, MRD can be considered as the preferred imaging modality in the diagnosis of acquired epiphora due to NLDO. By accurately identifying the underlying cause of NLDO, MRD can help determine the most appropriate treatment approach for patients and lead to better outcomes.

[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.

Etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO)

Primary acquired nasolacrimal duct obstruction, or PANDO, is a common adult lacrimal drainage disorder. The current treatment modality of dacryocystorhinostomy to bypass the obstructed nasolacrimal duct has excellent outcomes. However, the understanding of the disease etiopathogenesis needs to be revisited. There are not many studies that specifically assessed any hypothesis or ones that convincingly put forth the presumed or confirmed interpretations regarding the PANDO pathogenesis or the mechanisms or pathways involved therein. Histopathological evidence points to recurrent inflammation of the nasolacrimal duct, subsequent fibrosis, and the resultant obstruction. The disease etiopathogenesis is considered multifactorial. Several implicated suspects include anatomical narrowing of the bony nasolacrimal duct, vascular factors, local hormonal imbalance, microbial influence, nasal abnormalities, autonomic dysregulation, surfactants, lysosomal dysfunction, gastroesophageal reflux, tear proteins, and deranged local host defenses. The present work reviewed the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO) to gain insights into the present state of the understanding and the high-value translational implications of precisely decoding the disease etiology.

Computed Tomography Morphology of Affected versus Unaffected Sides in Patients with Unilateral Primary Acquired Nasolacrimal Duct Obstruction

BACKGROUND

This study aimed to describe the anatomical details of the bony nasolacrimal duct (BNLD) and adjacent nasal structures by analyzing computed tomography (CT) images, and to investigate their effects on the development of primary acquired nasolacrimal duct obstruction (PANDO).

METHODS

A total of 50 patients with unilateral PANDO who underwent dacryocystorhinostomy, with a mean age of 57.96 years, were included. The preoperative CT images were reviewed to measure the anteroposterior and transverse diameters of the BNLD at the entrance and exit levels, as well as the minimum transverse diameter along the tract. The sagittal CT images were analyzed to classify the shape of the bony canals into columnar, funnel, flare, and hourglass. The associated paranasal abnormalities, including nasal septum deviation (NSD), sinusitis, angle between the bony inferior turbinate and medial wall of the maxillary sinus, and mucosal thickness of the inferior turbinate, were investigated.

RESULTS

Fifty CT images were analyzed, and all parameters measured on both sides of the BNLD were not significantly different between the PANDO and non-PANDO sides, except for the minimum transverse diameter, which was significantly smaller on the PANDO side (p = 0.002). Columnar-shaped BNLD was the most common on both sides. No significant difference was observed in the incidence of paranasal abnormalities between sides; however, deviation of the septum toward the non-PANDO side was more common (67.9%).

CONCLUSIONS

A small minimum transverse diameter of the BNLD may be a risk factor for PANDO. The association between nasal abnormalities and PANDO was not remarkable.

Lacrimal Sac Anterior Border-Maxillary Line Distance: Effect on Endoscopic Dacryocystorhinostomy (EDCR) Surgery Results and NLDO-SS Questionnaire

This study aimed to investigate the effect of the maxillary line (ML)-lacrimal sac anterior border (LSA) distance on the results of endoscopic dacryocystorhinostomy (EDCR) operation. The study was designed retrospectively. The distance between LSA and ML was measured from preoperative paranasal sinus computed tomography (PNSCT) images. Nasolacrimal duct obstruction symptom score (NLDO-SS) was calculated before and after surgery. The endoscopically proven of the transition of the 2% fluorescein drop instilled into the eye to the nasal passage accepted as a surgical success. 47 patients included in the study and eight of them underwent bilateral EDCR. The average age of the patients was 50.3 ± 14.8. The LSA-ML distance was 4.2 ± 1.0 mm in all patients. The duration of surgery was found as 38.1 ± 6.1 min for each side. The preoperative NLDO-SS mean was 54.9 ± 11.7 and 22.2 ± 12.1 postoperatively (p = 0.000, CI = 28.9-36.2). Six patients (11%) required revision surgery. A statistically significant high positive correlation was found between duration of surgery and LSA-ML distance (p = 0.000, r = 0.840). There was a significant negative correlation between the duration of surgery and postoperative NLDO-SS (p = 0.041, r = -0.276). The LSA-ML distance calculated in this study was found to be significantly associated with the decrease in the duration of surgery and the NLDO-SS score obtained after surgery. However, more valid results can be obtained if similar studies are carried out in larger samples containing a sufficient number of revision cases.

Bony nasolacrimal duct size and outcomes of nasolacrimal silicone intubation for incomplete primary acquired nasolacrimal duct obstruction

Purpose

To investigate the association between the bony nasolacrimal duct (NLD) size and outcomes of nasolacrimal silicone intubation for incomplete primary acquired nasolacrimal duct obstruction (PANDO).

Methods

Patients who underwent silicone intubation for incomplete PANDO and had undergone facial computed tomography (CT) were included. Surgical success was judged by both epiphora improvement and normalized tear meniscus height (TMH; < 300 μm) on anterior segment optical coherence tomography at 3 months after tube removal. The area, major axis diameter, and minor axis diameter of the elliptic bony NLD sections were measured in 1.0 mm-thick axial CT images. These bony NLD sizes were analyzed for associations with surgical success and TMH normalization.

Results

Eighty-one eyes of 48 patients were investigated. The smallest area and the smallest minor axis diameter were significantly larger in the success group (49 eyes), compared with those in the failure group (median smallest minor axis diameter: 4.7 mm vs. 3.8 mm, P = 0.008, Mann–Whitney U test). There was also a tendency for the TMH normalization rate to significantly increase as the smallest area and the smallest minor axis diameter increased (P = 0.028 and 0.037, respectively, Fisher’s 2 × 4 tests). Under multivariable logistic regression analysis using generalized estimating equation, a larger smallest minor axis diameter was associated with success of the nasolacrimal silicone intubation (odds ratio: 2.481, 95% confidence interval: 1.143–5.384).

Conclusion

Surgical success of the nasolacrimal silicone intubation in incomplete PANDO is associated with a larger smallest minor axis diameter of the bony NLD. This finding will help understand the pathophysiology of surgical failure after nasolacrimal silicone intubation.

High-resolution computed tomography assessment of bony nasolacrimal parameters: variations due to age, sex, and facial features

PURPOSE

To compare nasolacrimal duct anatomy between gender, age, and facial features, and explore correlations between bony parameters.

METHODS

A retrospective case series of patients of four races who had high-resolution computed tomography (CT) 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. Mean age was slightly older for females (45.7 years) compared to males (42.5). Males have taller noses and wider faces. Nasolacrimal duct calibre correlated positively with age, male gender, and facial width, and negatively with nasal height. There was a tendency for nasolacrimal ducts to be longer in males.

CONCLUSION

The bony nasolacrimal duct is smaller in younger female patients. Having a taller nose and narrower upper face is also correlated with a smaller calibre duct. Acquired nasolacrimal duct obstruction in patients without these demographics or facial features may be more likely due to secondary causes.

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.

Relationship Between Primary Acquired Nasolacrimal Duct Obstruction, Paranasal Abnormalities and Nasal Septal Deviation

OBJECTIVES

This study aimed to investigate the relationship between nasal septal deviation and paranasal abnormalities in the etiology of primary acquired nasolacrimal duct obstruction (PANDO).

METHODS

A total of 37 (8 men, 29 women) patients (48 eyes with PANDO) between the ages 20 and 77 years (mean age, 52.8 ± 13.1 years) were included in the study. In the axial sections of paranasal sinus computed tomography, the transverse diameters at the most upper part and the most distal part of the nasolacrimal canal were separately measured. In addition, the relationships between PANDO and nasal septal deviation, inferior turbinate hypertrophy, agger nasi cells, paradoxical middle turbinate, concha bullosa, and the angle between the bony inferior turbinate and medial wall of the maxillary sinus were investigated.

RESULTS

A statistically significant relationship was found between PANDO and the axial location of septal deviation classification, axial angle of septal deviation classification, paradoxical middle turbinate, angle between the bony inferior turbinate and medial wall of the maxillary sinus and inferior meatus measure.

CONCLUSION

The authors concluded that the location and angle of the nasal septal deviation in the axial plane, width of the angle between the bony inferior turbinate and medial wall of the maxillary sinus, inferior meatus measure, and paradoxical middle turbinate may be effective factors in the etiology of PANDO.

Etiopathogenesis of Primary Acquired Nasolacrimal Duct Obstruction: What We Know and What We Need to Know

PURPOSE

To provide a systematic review of the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO).

METHODS

The authors performed a PubMed search of all articles published in English with specific reference to etiopathogenesis of PANDO or associations of PANDO. Data captured include demographics, study techniques, hypothesis, presumed or confirmed interpretations with regards to pathogenesis, mechanisms, or pathways. Specific emphasis was laid on addressing the lacunae and potential directions for future research.

RESULTS

Numerous factors are believed to contribute to the etiopathogenesis of PANDO. The basic pathogenesis involves inflammation, vascular congestion, mucosal edema, fibrosis, obstruction, and stasis. Bony nasolacrimal duct diameter does not appear to play a significant role. There is no convincing data to substantiate nose as the site of disease origin and nasal factors appear to be comorbidities. Hormonal mechanisms are more evidence-based but can only partly explain the pathogenesis. Vascular theories are based on the behavior of perilacrimal cavernous bodies, their autonomic control, and additional structural changes in the helical patterns of connective tissue fiber arrangements. Repeated vascular malfunction leading to structural epithelial and subepithelial changes currently appears to be the most evidence-based and accepted theory. Tear proteomics holds a promise in decoding the etiopathogenesis of PANDO, at least in part.

CONCLUSIONS

The etiopathogenesis of PANDO appears to be multifactorial. Hormonal microenvironments, vascular factors, and tear proteomics are promising candidates for further work. There is a need for focused work by Clinician-Scientists and the answers can have far reaching clinical implications.

Complex Stenoses and CT Features of the Nasolacrimal Canal in Congenital Nasolacrimal Duct Obstruction

PURPOSE

To study the CT appearance of the nasolacrimal canal (NLC) in cases of congenital nasolacrimal duct obstruction (CNLDO) where there is a tactile sensation of a hard contact (HC) stop in the duct preventing stent intubation.

METHODS

The authors retrospectively reviewed all consecutive cases of chronic CNLDO observed between 2003 and 2018 in which an apparent HC obstruction prevented nasolacrimal intubation. CT scans were reviewed to determine the cause of probing failure: distal stenosis, loss of parallelism of the NLC walls, abnormal angulations or an adjacent obstacle blocking tear outflow.

RESULTS

Nine patients (12 sides) met the following criteria: CNLDO + HC + probing failure. The mean age at the time of the first HC was 3.9 years (range: 0.8-8.1 years) and at the time of a second confirmation of HC with subsequent dacryocystorhinostomy was 7.8 years (range: 4.1-9.2 years). Nasolacrimal duct opacification was noted in 33% of cases (4/12). Abnormalities of the NLC occurred in 8 of the 12 cases of CNLDO (8/12 = 66.6%) and on the asymptomatic side in 1 case (1/6 = 16.6%). A canine tooth bud situated in the same plane as the NLC was observed in 9 cases of CNLDO (9/12 = 75%) and on the asymptomatic side in 2 cases (2/6 = 33.3%).

CONCLUSIONS

HC noted during probing is a sensitive but relatively nonspecific sign which, nevertheless, does indicate either a complex obstruction or at least potential intubation difficulties. As confirmed by CT imaging, a significant anatomical variant is not necessarily predictive of epiphora, but nevertheless may complicate the intubation procedure.The authors describe hard contact palpation during probing for CLNDO and its relationship to anatomic location and etiologies of obstruction in the nasolacrimal canal by CT imaging.

Morphometric Measurements of Bony Nasolacrimal Canal in Children

OBJECTIVE

Morphology and dimensions of the bony nasolacrimal canal duct (BNLD) as a key factor in the development of primary acquired nasolacrimal duct obstruction. We aimed to obtain detailed morphometric analysis of BNLD in children without nasolacrimal duct pathology by using computed tomography and provide standard measurements by means of age which could be utilized in planning management or in invasive interventions.

METHODS

Picture Archiving Communication Systems database of our hospital's radiology department was searched for this retrospective study. Subjects were under 18 years of age who had undergone a paranasal, maxillofacial, or temporal bone high-resolution computed tomography scan in last 2 years with various indications. Those with fractures including facial bones and/or nasolacrimal canal or history of nasolacrimal duct pathology were excluded from the study. We measured the diameter, angle, and surface area of BNLD.

RESULTS

A total number of 136 subjects (86 boys, 50 girls) were included in the study. The average age was 7.3 ± 5.1 years. We documented statistically significantly positive correlation between all measured diameters and ages (P < 0.001), whereas there was a negative association between mean angle and age (P < 0.001). Mean angle is defined as the angle between BNLD and nasal floor. The surface area of BNLD was found to be significantly increasing depending on age (P < 0.001). However, we could not find any significant association between gender and measured parameters (P > 0.050).

CONCLUSION

Our study demonstrated that development of BNLD continues during childhood, regardless of gender.

Nasolacrimal System Aeration on Computed Tomographic Imaging: Sex and Age Variation

PURPOSE

To investigate variation in aeration of the nasolacrimal drainage system between age groups and genders, and to report the reliability of repeated aeration grading and nasolacrimal canal measurements on CT.

METHODS

Retrospective review of CT images from 92 individuals, 60 female and 32 male, was conducted by 3 independent reviewers for the presence of air within the nasolacrimal drainage system. Diameter and area measurements were also obtained at the smallest identifiable portion of the nasolacrimal canal by 2 independent reviewers.

RESULTS

When air is present on CT, it is seen more fully throughout the nasolacrimal system in men as compared to women. Age data demonstrate that patients from the third and fourth decade have significantly more aeration than older patients. Diameter and area of the nasolacrimal duct within the canal at its narrowest point revealed no correlation with sex, age, or nasolacrimal system aeration. Inter-reviewer reliability shows strong repeatability of aeration grading and nasolacrimal duct measurements between multiple reviewers.

CONCLUSIONS

The results suggest CT is reliable and repeatable modality to assess nasolacrimal system aeration and nasolacrimal duct diameter. Decreased aeration of the nasolacrimal system in females and the elderly mirrors epidemiologic trends for those at risk to develop primary acquired nasolacrimal duct obstruction. Variables in nasolacrimal drainage system anatomy, specifically nasolacrimal duct diameter and area, did not vary between sexes or age groups, suggesting aeration may be an overlooked variable in nasolacrimal system function.

Three-Dimensional Reconstruction of the Bony Nasolacrimal Canal by Automated Segmentation of Computed Tomography Images

Objective

To apply a fully automated method to quantify the 3D structure of the bony nasolacrimal canal (NLC) from CT scans whereby the size and main morphometric characteristics of the canal can be determined.

Design

Cross-sectional study.

Subjects

36 eyes of 18 healthy individuals.

Methods

Using software designed to detect the boundaries of the NLC on CT images, 36 NLC reconstructions were prepared. These reconstructions were then used to calculate NLC volume. The NLC axis in each case was determined according to a polygonal model and to 2^nd, 3^rd and 4^th degree polynomials. From these models, NLC sectional areas and length were determined. For each variable, descriptive statistics and normality tests (Kolmogorov-Smirnov and Shapiro-Wilk) were established.

Main Outcome Measures

Time for segmentation, NLC volume, axis, sectional areas and length.

Results

Mean processing time was around 30 seconds for segmenting each canal. All the variables generated were normally distributed. Measurements obtained using the four models polygonal, 2^nd, 3^rd and 4^th degree polynomial, respectively, were: mean canal length 14.74, 14.3, 14.80, and 15.03 mm; mean sectional area 15.15, 11.77, 11.43, and 11.56 mm²; minimum sectional area 8.69, 7.62, 7.40, and 7.19 mm²; and mean depth of minimum sectional area (craniocaudal) 7.85, 7.71, 8.19, and 8.08 mm.

Conclusion

The method proposed automatically reconstructs the NLC on CT scans. Using these reconstructions, morphometric measurements can be calculated from NLC axis estimates based on polygonal and 2^nd, 3^rd and 4^th polynomial models.

A Possible Cause of Nasolacrimal Duct Obstruction: Narrow Angle Between Inferior Turbinate and Upper Part of the Medial Wall of the Maxillary Sinus

BACKGROUND

To search the relationships between the primary nasolacrimal duct obstruction and the angle between the bony inferior turbinate and upper part of the medial wall of the maxillary sinus.

DESIGN

Retrospective study.

PARTICIPANTS AND METHODS

Computed tomography findings of 35 patients with primary nasolacrimal duct obstruction and 100 sides of 50 individuals were reviewed. While the study group was composed of patients who had external dacryocystorhinostomy surgery, the control group was composed of patients who had CT scans due to headache, sinusitis and smell dysfunction. Epiphora complaint was evaluated with the lacrimal syringing. The exclusion criteria were: age less than 20 years, previous nose, sinus, turbinate or lacrimal surgery, prior history of maxillofacial fracture, nasopharyngeal malignancy, reflex hypersecretion, and associated pathology of the lacrimal canaliculi.

MAIN OUTCOME MEASURES

The angle of inferior turbinate.

RESULTS

The mean angles were 53.2° (range, 37.9-82.9°) for affected side of the study group, 58.6° (range, 32-85.3°) for the unaffected side of the study group and 56.8° (range, 41.2-76.9°) in the control group. The difference between the angles was statistically significant between the study and the control groups (p < 0.05). The difference between the operated and non-operated sides of the study group was also statistically significant (p < 0.05).

CONCLUSION

Although this study was performed in a small group, we thought that the narrow angle between the bony inferior turbinate and upper part of the medial wall of the maxillary sinus might be a possible causative factor in primary acquired nasolacrimal duct obstructions.

Comparison of bony nasolacrimal canal narrowing with or without primary acquired nasolacrimal duct obstruction in a Japanese population

PURPOSE

To compare the minimum diameter of the nasolacrimal canal and its location between patients with or without primary acquired nasolacrimal duct obstruction (NLDO) in a Japanese population.

METHODS

One hundred one patients with unilateral primary acquired NLDO (Group A, 101 affected sides; Group B, 101 unaffected sides) and 50 non-NLDO patients (Group C, 100 sides) were included. Anteroposterior and transverse diameters were measured at the canal entrance and the shortest point using contiguous 1-mm axial computed tomographic images. Canal shapes were classified into 2 types: the "funnel" type (a canal with both minimum diameters at the canal entrance) and the "hourglass" type (a canal with at least one minimum diameter in the canal). The distance from the entrance to the part with the shortest diameter was measured on sides with the hourglass type.

RESULTS

The funnel type was found more frequently in Groups A and B than in Group C (p<0.050), although a difference was not found between Groups A and B (p=0.778). The distance of the transverse diameter was significantly shorter in Groups A and B than Group C (p<0.050), although no significant difference was found in this distance between Groups A and B (p=1.000). There were no significant differences between the groups for each value except for the above mentioned (p>0.050).

CONCLUSIONS

Primary acquired NLDO patients exhibited the funnel type more frequently or there was a shorter distance from the entrance to the part with the shortest diameter than non-NLDO patients, which may enhance the risk of primary acquired NLDO.

Nasolacrimal system aeration on computed tomographic imaging: effects of patient positioning and scan orientation

Purpose

To determine the impact of patient positioning and scan orientation on the appearance of air in the nasolacrimal drainage system on computed tomography (CT) imaging, and the repeatability of the observations.

Methods

This was a retrospective analysis of CT images for 92 patients.

Results

Air was found to be present more fully in the upright-position group as compared with the supine-position group. Comparing axial and coronal scan orientation, no difference in aeration was found, except for the nasolacrimal duct in the upright-position group.

Conclusion

Patient position should be accounted for in diagnostic conclusions and treatment decisions based on CT.

The orientation of the lacrimal fossa to the bony nasolacrimal canal: an anatomical study

PURPOSE

To examine the relative positions of the lacrimal fossa (LF) and the bony nasolacrimal canal (BNLC) in relation to each other and a reference plane.

METHODS

Forty-two orbits and BNLCs from 21 Asian cadavers (9 men and 12 women; average age at death, 84.4 years; range, 70-99 years) had been fixed in 10% buffered formalin before use. After exposing the LF and the medial half of the BNLC, the authors measured the angles of the longitudinal axis of the LF and the BNLC relative to the aesthetic horizontal plane respectively. Based on these values, the relative orientation of the LF and the BNLC was determined and defined in terms of Δ BNLC-LF. A positive Δ BNLC-LF represents a nasolacrimal canal that descends posteriorly relative to the LF.

RESULTS

The mean LF, BNLC, and Δ BNLC-LF were 9.5°, 19.8°, and 10.3°, respectively. In 39 passages (92.9%), the Δ BNLC-LF was positive, representing a nasolacrimal canal that is more posteriorly oriented than the LF. In 3 passages (7.1%), the Δ BNLC-LF was equal to or less than 0°; 2 of them (4.8%) had a straight course and 1 passage (2.4%) had a negative value.

CONCLUSIONS

In most patients, the BNLC is directed more posteriorly than the LF. This finding may help in preventing an inadvertent false passage during probing and intubation in patients with epiphora.

Update on imaging of the lacrimal drainage system

Epiphora is a common problem seen by the ophthalmologist. There are numerous etiologies of a watering eye, and the underlying diagnosis is not always clear. A variety of in-office examination techniques and procedures exist to aid with diagnosis and determination of appropriate therapy, but sometimes the diagnosis remains elusive, or an instituted therapy fails. Lacrimal imaging, particularly in these cases, can be helpful in assessing the function and anatomy of the lacrimal drainage system. This review serves to examine the literature of the last 10 years concerning imaging of the lacrimal drainage system.