Cone Beam Computed Tomography (CBCT) was employed to evaluate the differences in morphometric parameters of the bony nasolacrimal canals (BNLDs) between primary acquired nasolacrimal duct obstruction (PANDO) patients(patients with primary acquired nasolacrimal duct obstruction (PANDO ) (both the affected and unaffected sides) and control subjects (control sides). Seven parameters of bilateral BNLDs were measured retrospectively in 42 unilateral patients (Case group) and 14 controls (Control group). Comparison was made between Case group and Control group for age and gender, and the seven parameters were compared among the affected sides, the unaffected sides and control sides. In both the affected sides and the unaffected sides relative to the control sides, the length of BNLD was significantly longer (p<0.001, p<0.001, respectively), while the angle of NLNF  was larger (p<0.001, p<0.001, respectively), and the angle of lacrimal sac-BNLD was smaller (p=0.02, p=0.01, respectively). However, no significant differences were shown between the two sides within patients (all p>0.05). Moreover, other parameters showed no statistical differences among the affected sides, the unaffected sides and the control sides (all p>0.05). There was no statistical difference in any parameters between genders or among different ages within PANDO patients (all p>0.05). A shorter length of BNLD, a larger angle of NLNF, and a smaller angle of lacrimal sac-BNLD in both sides of PANDO patients may be correlated with the occurrence of PANDO. The lack of difference between the affected and unaffected sides of the Case group and some overlap of measured parameters between Case and Control subjects suggest that morphometric changes may be only one of the factors that contribute to the development of PANDO.

Jing Li, Li Ou, Liang Jia. Morphometric Assessment of the Bony Nasolacrimal Canal in Patients with Primary Acquired Nasolacrimal Duct Obstruction by Cone Beam Computed Tomography. Frontiers in Medical Science Research (2024), Vol. 6, Issue 5: 69-76. https://doi.org/10.25236/FMSR.2024.060510.

[1] Woog J. The incidence of symptomatic acquired lacrimal outflow obstruction among residents of Olmsted County, Minnesota, 1976-2000 (an American Ophthalmological Society thesis). Transactions of the American Ophthalmological Society 2007; 105: 649-666

[2] Goel R, Nagpal S, Kumar S, et al. Transcanalicular Laser-Assisted Dacryocystorhinostomy With Endonasal Augmentation in Primary Nasolacrimal Duct Obstruction: Our Experience. Ophthalmic plastic and reconstructive surgery 2017; 33: 408-412. DOI: 10.1097/iop.0000000000000802 

[3] Ohtomo K, Ueta T, Toyama T, et al. Predisposing factors for primary acquired nasolacrimal duct obstruction. Graefes Archive for Clinical & Experimental Ophthalmology 2013; 251: 1835-1839. DOI: 10.1007/s00417-013-2288-5

[4] Linberg J, McCormick S. Primary acquired nasolacrimal duct obstruction. A clinicopathologic report and biopsy technique. Ophthalmology 1986; 93: 1055-1063

[5] Seider N, Miller B, Beiran I. Topical glaucoma therapy as a risk factor for nasolacrimal duct obstruction. American journal of ophthalmology 2008; 145: 120-123. DOI: 10.1097/IEB. 0b013e31817 d89b9 

[6] Janssen A, Mansour K, Bos J, et al. Diameter of the bony lacrimal canal: normal values and values related to nasolacrimal duct obstruction: assessment with CT. AJNR American journal of neuroradiology 2001; 22: 845-850. DOI: 10.1016/S0925-4927(01)00075-0 

[7] Shigeta K, Takegoshi H, Kikuchi S. Sex and age differences in the bony nasolacrimal canal: an anatomical study. Archives of ophthalmology (Chicago, Ill: 1960) 2007; 125: 1677-1681. DOI: 10.1001/archopht.125.12.1677 

[8] McCormick A, Sloan B. The diameter of the nasolacrimal canal measured by computed tomography: gender and racial differences. Clin Exp Ophthalmol 2009;37:357-361. DOI: 10.1111/j.1442-9071. 2009. 02042.x

[9] Takahashi Y, Kakizaki H, Nakano T. Bony Nasolacrimal Duct Entrance Diameter: Gender Difference in Cadaveric Study. Ophthalmic plastic and reconstructive surgery 2011;27:204-205. DOI: 10.1097/IOP.0b013e3182078e47 

[10] Frcophth MC, Franzco BS. The diameter of the nasolacrimal canal measured by computed tomography: gender and racial differences. Clin Exp Ophthalmol 2010;37:357-361. DOI: 10.1111/j. 1442-9071.2009.02042.x

[11] Takahashi Y, Nakata K, Miyazaki H, et al. Comparison of bony nasolacrimal canal narrowing with or without primary acquired nasolacrimal duct obstruction in a Japanese population. Ophthalmic plastic and reconstructive surgery 2014;30:434-438. DOI: 10.1097/IOP.0000000000000238 

[12] Estes J, Tsiouris A, Christos P, et al. Three-dimensional volumetric assessment of the nasolacrimal duct in patients with obstruction. Ophthalmic plastic and reconstructive surgery 2015;31:211-214.DOI: 10.1097/IOP.0000000000000259 

[13] Ramey N, Hoang J, Richard M. Multidetector CT of nasolacrimal canal morphology: normal variation by age, gender, and race. Ophthalmic plastic and reconstructive surgery 2013;29:475-480. DOI: 10.1097/IOP.0b013e3182a230b0 

[14] Qin L, Wang J, Jia L. Evaluation of nasolacrimal duct parameters and volume in patients with primary acquired nasolacrimal duct obstruction. Acad J Chin PLA Med Sch 2020;41:1006-1010(in Chinese)