Morphometric Evaluation of Bony Nasolacrimal Canal in a Caucasian Population with Primary Acquired Nasolacrimal Duct Obstruction: A Multidetector Computed Tomography Study

Morphometric analysis of bony nasolacrimal canal and sinonasal anatomical variations in primary acquired nasolacrimal duct obstruction

OBJECTIVE

This study aims to assess morphometric variations in bony nasolacrimal ducts (BNLDs) and sinonasal anatomy in Asian patients with unilateral primary acquired nasolacrimal duct obstruction (PANDO) through computed tomography (CT).

METHODS

We enrolled 34 patients with unilateral PANDO who underwent endoscopic dacryocystorhinostomy, alongside 34 age- and sex-matched control patients without documented epiphora complaints. We compared BNLD and sinonasal parameters on CT images between the affected and unaffected sides of PANDO patients and the control group.

RESULTS

The entrance area of the BNLD was larger on the affected side of unilateral PANDO patients compared to both the unaffected side (p = 0.012) and the control group (p = 0.046). The open angle in the coronal plane was greater on both the affected (p = 0.044) and unaffected side (p = 0.028) than in the control group. Minimal area and distal area in the axial plane showed no differences among the 3 groups. Paranasal parameters did not differ between the study and control groups. More patients in the study group had superiorly located nasal septum deviation than the control group (p = 0.048). A trend suggested that more patients in the study group had anteriorly located nasal septum deviation than the control group (p = 0.056), although not reaching statistical significance.

CONCLUSION

The increased angular tilt in PANDO patients could impede fluid drainage from a fluidics standpoint. The larger BNLD area on the affected side reflects inflammation-induced osteolysis. Additionally, sinonasal variations, particularly nasal septum deviation at the anterior and superior half, have been identified as contributing to a higher risk of PANDO.

Investigating the Morphology of the Nasolacrimal Canal in Cone Beam Computed Tomography Images and Its Relationship with Age and Gender

INTRODUCTION

Nasal and paranasal anatomical structures are closely related to the nasolacrimal canal (NLC). As a result of this anatomical relationship, several studies have reported that nasal and paranasal sinus pathologies often play a major role in the etiology of nasolacrimal duct obstruction. The purpose of this study was to investigate the anteroposterior diameter, transverse diameter, length and angle of the bony NLC with nasal floor on the right and left by using cone beam computed tomography (CBCT) and to explore the influence of gender and age on the above-mentioned parameters.

METHODS

The current study was conducted by examining the archive of primary CBCT images of patients who were referred for medical imaging to a private maxillofacial radiology clinic in Ahvaz, Iran, in 2020. In axial images, anteroposterior diameter and transverse diameter of the canal in the level of infraorbital were measured. In sagittal images, the length of the NLC was evaluated from the most proximal to the most distal part. Also, to examine the canal pathway, the angle between the canal and the floor of the nasal cavity was measured. Finally, all patient data, including age, gender and canal dimensions, diameter and path, was collected in the information form and referred to the statistics consultant for analysis.

RESULTS

In the present study we included information of primary CBCT images of 126 patients who had been referred to a private maxillofacial radiology in Ahvaz, Iran, in 2020. Participants' average age was 28.22±8.13 years for women and 31.54±8.12 years for men, and a small age difference between sexes was seen. The average angle of the right canal with nasal floor was 108.29±7.96º for men and 113.70±7.57º for women, with a significant statistical difference by gender being observed. The mean values of the right channel length were 10.47±2.56 mm for women and 12.54±2.40 mm for men, and the difference between them was statistically significant. The mean values of the left canal length were 109.30±8.67 mm for women and 114.52±9.01 mm for men, and the difference between them was also statistically significant.

CONCLUSION

This study provides useful information on the morphometric properties of the bony nasal canal. Careful anatomical knowledge about the morphology of the bony nasal canal may help physicians to plan the treatment options. As the present study raises some concerns related to the age and gender differences in nasopalatine canal morphology that may affect patients' diagnosis and treatment, dentists are recommended to use CBCT images as well as additional techniques with this regard.

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.

Evaluation of primary acquired nasolacrimal duct obstruction: Comparison of CT-DCG and dacryoendoscopy in accurately localizing the lacrimal drainage obstructions

OBJECTIVE

To correlate and evaluate the power and limitations of CT-DCG in determining the level and type of lacrimal duct obstruction in comparison to dacryoendoscopy in patients clinically suspected to be having partial or complete primary acquired nasolacrimal duct obstruction (PANDO).

METHODS

A retrospective chart review was performed on 1232 lacrimal drainage systems of 957 patients who suffered from primary acquired nasolacrimal duct obstruction (PANDO) at Shanghai Ninth People's Hospital. Patients were examined with CT-DCG and correlated with dacryoendoscopy and the findings of clinical examination.

RESULTS

Of the studied patients, 173 were men and 784 were women with an age range of 18-93 years. Of the 1232 lacrimal pathways, good CT-DCG images could be obtained in 980 cases and dacryoendoscopy in 957 cases. Of these complete obstructions were noted in 81% (794/980), and partial obstructions were identified in 19% (186/980) with CT-DCG. CT-DCG and dacryoendoscopy showed 68.4% agreement for the type of the obstruction and 63% for the level of the obstruction. The majority of the obstructions occurred at the sac-duct junction (62.5%) followed by the upper half of the nasolacrimal duct (27.5%). There was a significant difference in the correlation of the obstruction type with age group and with the duration of symptoms. As the duration of symptoms increased, the proportion of complete lacrimal duct obstructions as shown on CT-DCG images increased and the proportion of incomplete obstruction decreased (p = 0.015).

CONCLUSIONS

The junction of lacrimal sac and nasolacrimal duct was the most common obstruction site. Age and the duration of symptoms influenced the type of obstruction noted. The degree and level of agreement between the investigations was moderate. A combination of CT-DCG and Dacryoendoscopy could together identify the location more accurately.

[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.

[Biometric characteristics of the lacrimal passages in healthy individuals and in patients with nasolacrimal duct obstruction]

Despite an obvious interest in the processes occurring in the lacrimal passages in their obstruction, there is few articles analyzing their biometric parameters.

PURPOSE

The study investigates the biometric characteristics of the lacrimal passages in healthy individuals and in patients with nasolacrimal duct obstruction.

MATERIAL AND METHODS

The study included 81 cases of partial nasolacrimal duct obstruction and 38 cases without tear drainage insufficiency. All patients underwent computed tomography with dacryocystography. Analysis of the biometric parameters involved calculation of the length, volume, and average sectional area of the nasolacrimal duct and the nasolacrimal bony canal. The ratio R4/16l was calculated (where R is the radius of the nasolacrimal duct; l is the length of the nasolacrimal duct). The normality of values was assessed using the Shapiro-Wilk test. Intergroup differences were assessed using the Mann-Whitney test and t-statistics for independent samples. Correlation analysis was performed according to the Spearman method. ROC analysis was carried out. Differences were considered significant at p≤0.05.

RESULTS

There were significant differences in the volume (p=0.004) and the average sectional area of the nasolacrimal duct (p=0.014), as well as in the length of the nasolacrimal canal (p=0.034). Relationships were established between the age of patients without tear drainage insufficiency and the length of the nasolacrimal canal (p=0.042); the length of the nasolacrimal canal and the volume of the nasolacrimal duct (p=0.034), as well as the volume of the nasolacrimal duct and the nasolacrimal canal in partial nasolacrimal duct obstruction (p=0.017). The AUC of the R4/16l ratio in the ROC analysis was 0.653 (p=0.007).

CONCLUSION

In addition to the obvious differences, it was found that the length of the nasolacrimal bony canal significantly differed in the subjects of both study groups. We considered the tear ducts as a hydrodynamic system obeying Poiseuille's law, so we calculated the ratio R4/16l. The value of this ratio varied (p=0.016), and the ROC analysis showed high sensitivity and specificity of the criterion. This makes it possible to use this ratio as a diagnostic criterion for partial nasolacrimal duct obstruction.

Quantitative analysis of both lacrimal glands in unilateral primary acquired nasolacrimal duct obstruction, based on three-dimensional fast spin echo-Cube-Flex

OBJECTIVE

To investigate whether unilateral primary acquired nasolacrimal duct obstruction (PANDO) changes the volume and water fraction of both lacrimal glands, using three-dimensional fast spin echo (3D-FSE)-Cube-Flex images, and to identify whether the lacrimal gland is a target organ in this disease.

METHODS

3D-FSE-Cube-Flex images of both lacrimal glands in 25 healthy volunteers and 31 patients with unilateral PANDO were retrospectively reviewed. The differences in volume and water content in the lacrimal glands between the controls, non-PANDO side, and PANDO side groups were examined. Moreover, the associations between magnetic resonance imaging (MRI) parameters and disease duration were assessed with correlation analysis.

RESULTS

The lacrimal gland volumes were not significantly different between the PANDO and non-PANDO side groups, compared to the control group (P = 0.484). However, the gland volumes tended to be increased bilaterally in patients with PANDO. In contrast, the gland water fractions in the PANDO and non-PANDO side groups were significantly higher than those in the control group (P = 0.009 and P = 0.014, respectively), and similar between the non-PANDO and PANDO side groups (P = 0.897). No correlation was found between the disease duration and the gland MRI parameters (volume and water fraction).

CONCLUSIONS

Both lacrimal glands are affected by unilateral PANDO. A change in the water fraction of these glands appears to precede the change in volume and may be a sensitive early indicator.

Computed tomographic assessment of the lacrimal sac fossa in southwest population of Iran

To determine the morphology of the lacrimal sac fossa and bony nasolacrimal duct using computed tomography for obtaining detailed anatomical understanding of the drainage system and utilizing these measurements in planning for dacryocystorhinostomy (DCR) and nasolacrimal duct (NLD) obstruction in normal southwest (SW) population of Iran. One-hundred-sixty-five cases referred for the diagnosis of neuro-ophthalmic conditions were retrospectively studied. Measurements of lacrimal sac fossa were taken on three anatomical sections (upper, middle, and lower planes) utilizing a digital caliper/protractor instrument. Lacrimal thickness and two measurements of maxillary bone thickness were taken at each plane—namely, the “midpoint thickness” and the “maximum thickness.” The anterior extent of the nasal mucosa and NLD width was also evaluated. The mean maximum thickness of the maxillary bone at the three anatomical planes of the lacrimal sac fossa was 4.07 mm, 4.78 mm, and 5.60 mm, respectively. The midpoint thickness of the maxillary bone at each plane was 2.38 mm, 1.99 mm, and 1.68 mm, respectively, in both sexs. The lacrimal bone thickness at each level was 0.76 mm, 0.69 mm, and 0.67 mm, respectively. The proportion of the lacrimal sac fossa comprising the lacrimal bone at lower plane was 43.57% and showed a positive correlation with age (P=0.01). The mean anteroposterior bony nasolacrimal diameter was 5.94 mm with no significant difference between patient sex and age. According to the results, its indicate that performing an osteotomy during DCR could be easier in the Iranian SW population compared to other ethnics.

Anatomy of lacrimal sac fossa affecting success rate in endoscopic and external dacryocystorhinostomy surgery in Mongolians

To study the affect of anatomical variance of lacrimal sac fossa on dacryocystorhinostomies (DCR) performed by the traditional external (EX-DCR) approach or an endoscopic (EN-DCR) endonasal approach. A total of 292 consecutive cases with primary nasolacrimal obstruction underwent DCR surgery. Orbital computed tomography scan was used to measure lacrimal sac fossa and other related structures and Lac-Q questionnaire was used to compare surgery result. Maxillary portion of lacrimal sac fossa is thicker in failed surgery group than successful surgery group (P<0.05). Lateral nasal structures (uncinate process, operculum of the middle turbinate, agger nasi) are dominantly adjusting to lacrimal sac fossa in failed surgery group (P<0.05). Patients who underwent EX-DCR has a 6.0-point and EN-DCR group 11.0-point improvement (P<0.016) in Lac-Q questionnaire. Patients who have a thick frontal process of the maxilla and uncinate process, operculum of the middle turbinate, ethmoid cells adjusting to lacrimal fossa are prone to have recurrence of nasolacrimal duct obstruction after DCR surgery. The EN-DCR and the EX-DCR approach have an equivalent surgical success rate but improvement in quality of life by using the Lac-Q questionnaire is greater in the endoscopic group when compared with the external.

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.

3D morphological classification of the nasolacrimal duct: Anatomical study for planning treatment of tear drainage obstruction

BACKGROUND

The purpose of this study is to analyze and classify morphological features of the nasolacrimal duct (NLD) through 3D reconstruction to help understand the causes and treatment of NLD obstruction.

METHODS

In this study, we included 63 males and 55 females who underwent autopsy without NLD obstruction with ages ranging from 20 to 78 years. The NLD was defined from the lacrimal fossa to the opening of the BNLD to the inferior meatus, and all continuous CT images showing the NLD were selected. Segmentation was performed semi-automatically, and the reconstruction and measurement of NLD was performed using the Mimics program.

RESULTS

Overall NLD length, bony nasolacrimal duct (BNLD) length, anteroposterior and transverse diameters at the entrance to the BNLD, anteroposterior and transverse smallest diameters of the BNLD, BNLD volume, and lacrimal sac BNLD angle were significantly higher in males than females (p < .05). BNLD direction in the coronal plane was slightly more likely to be inward. The most common type in both sexes was cylinder type (42.0%), males were more likely to have lower-thicker types (34.1%), and females more likely to have upper-thicker types (22.7%).

CONCLUSION

There were sex differences in NLD measurements, and females had significantly smaller NLDs. These results may partially explain the increased prevalence of primary acquired NLD obstruction in females. The BNLD tends toward the midline, and inclines posteriorly.

Sinonasal Anatomical Variations and Primary Acquired Nasolacrimal Duct Obstruction: A Single Centre, Case-Control Investigation

Objective

Primary acquired nasolacrimal duct obstruction (PANDO) is an idiopathic narrowing of the nasolacrimal duct caused by chronic inflammation and consecutive stenosis of the nasal tissue. In the current investigation, we aimed to study the etiopathogenic role of sinonasal anatomical abnormalities and paranasal inflammatory pathologies in PANDO.

Materials and Methods

Computed tomography (CT) findings of 459 patients who were diagnosed with unilateral PANDO between April 2009 and March 2017 were compared with that of a control group, which comprised 200 subjects without nasolacrimal duct obstruction who had been referred to the ear nose throat (ENT) clinic with the complaint of vertigo and headache. A radiologist (R. S.) masked to the clinical situation of participants retrospectively examined their CT findings.

Results

The prevalence of deviated nasal septum was found to be strongly associated with PANDO incidence (55.3% on PANDO side of patients vs. 28.3% among controls; p<0.001). Significant increases, albeit of smaller magnitude, were also observed in the relative frequency of Agger nasi cells and maxillary sinusitis on the PANDO side of the subjects (14.6% and 27.0%, respectively) compared to controls (9.5% and 20.6%, respectively) (p=0.023 and p=0.038, respectively). Unilateral PANDO was also found to be robustly associated with an ipsilateral deviated nasal septum (p<0.001). The odds of septal deviation occurrence were 3.037 times (95% Confidence Interval (CI): 2.303-3.990; p<0.001) more on the PANDO than the non-PANDO side of the studied cases.

Conclusion

Ipsilaterally deviated nasal septum appears to have a role in the development of unilateral primary acquired obstructive disease of the lacrimal drainage system. The incidence of PANDO might also be affected by Agger nasi cells and maxillary sinusitis. Multicenter studies are essential to further elucidate the interaction between type, severity, extent, and dimensions of different pathologies with nasolacrimal duct obstruction.

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.

Measuring nasolacrimal duct volume using computed tomography images in nasolacrimal duct obstruction patients in Korean

AIM

To investigate nasolacrimal duct (NLD) volume in Korean patients and to examine the correlation between NLD volume and obstruction.

METHODS

Of patients who underwent orbital computed tomography from March 2013 to January 2016, patients diagnosed with NLD obstruction were classified into the patient group and patients without obstruction were classified into the control group. The NLD volume was measured using the Image J program, which showed the NLD in axial, coronal, and sagittal images on computed tomography.

RESULTS

The average value of men's NLD volume, 265.33±90.57 mm³, was significantly larger than women's, 211.87±68.61 mm³ (P=0.009). In the patient group, the NLD volume of the obstructed eyes, 242.49±82.93 mm³, and the non-obstructed eyes, 225.20±73.20 mm³, were significantly higher than the control group, 217.61±82.04 mm³ (P<0.001, P<0.001).

CONCLUSION

The NLD volume is larger in men than in women in Korean adults. If there is NLD obstruction in women, the NLD volume is larger and it is judged that inflammatory reaction caused a chronic change in the bone around the NLD and affect the measurement of NLD volume.

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.

Examination of Nasolacrimal Duct Morphometry Using Cone Beam Computed Tomography in Patients With Unilateral Cleft Lip/Palate

OBJECTIVE

The cleft lip/palate (CLP) deformity negatively affects the anatomy of the nasal cavity and maxilla. The effects of this deformity on the lacrimal system have been unidentified yet. This study aimed to evaluate the morphometric changes in the nasolacrimal duct using cone-beam computed tomography (CBCT) in patients with unilateral CLP.

MATERIALS AND METHODS

Retrospective bilateral measurements of the narrowest transversal diameters and the lengths of the nasolacrimal ducts were made for the affected and unaffected sides of 28 patients with CLP and 28 control patients, using the CBCT images. The measurements were statistically compared.

RESULTS

The mean narrowest transversal diameter of the nasolacrimal duct for the affected side of the patients with unilateral CLP was statistically significantly narrower than the unaffected side (P = 0.01). There were no statistically significant differences between the control group and the affected and unaffected sides of patient group with unilateral CLP regarding the nasolacrimal duct diameter. The differences were not statistically significant among all groups regarding the mean nasolacrimal duct length.

CONCLUSION

The diameter of the nasolacrimal duct at the affected side of unilateral CLP was narrower than the unaffected side. According to this result, the CLP deformity can have an effect on the nasolacrimal duct diameter. However, CLP might not affect the nasolacrimal duct length.