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

ABSTRACT

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.

KEYWORDS:

• Computed tomography
• frontal bone
• lacrimal manipulation
• nasolacrimal duct
• primary acquired nasolacrimal duct obstruction

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors contributions

Conceptualization, Y.L., A.J. and S.N.; methodology, Y.L., A.J. and S.N.; formal analysis, Y.L.; investigation, Y.L., S.C., A.W., M.K. and R.D.; resources, F.L. and R.Z.; data curation, Y.L., H.Y.; writing—original draft preparation, Y.L.; writing—review and editing, Y.L., A.J. and S.N.; visualization, Y.L.; supervision, X.L., D.H. and R.C. All authors have read and agreed to the published version of the manuscript.

Data availability statement

The data that support the findings of this study are not publicly available as the information contained could compromise the privacy of research participants. Further inquiries can be directed to the corresponding author.

Additional information

Funding

This study was partly supported by the Special Correspondent Project of Guangdong Rural Science, and Technology (No. KTPYJ2021021), the Fundamental Research Funds of the State Key Laboratory of Ophthalmology (No.30306020240020219), the Pearl River Scholar Tianshan Talent Cooperation’s Expert Studio Innovation Team (No. KDYY202018), and Sun Yat-Sen University Clinical Research 5010 Program (No. 2014014).