Background: The aim of this study was to investigate the diameters of the bony nasolacrimal canal by computed tomography in normal adult Mongolian population and the effect of gender and age on the nasolacrimal canal diameter. Methods: Using standart tomographic images, we measured the diameters, angle between the bony canal and nasal floor and length of the bony nasolacrimal duct in 150 patients without nasolacrimal duct disease. Results: The anterioposterior diameter of the bony nasolacrimal canal was 6.49± 1.06mm, transverse diameter was 4.56±0.9mm, angle between the bony canal and nasal floor was 69.6±8.1o. No significant difference in anterioposterior diameter and transverse diameter in gender. The angle between the bony canal and nasal floor was significantly greater in male. Conclusions This study may contribute to the establishment of a detailed anatomical and morphometric baseline of the bony nasolacrimal canal and provide useful information for the planning of interventions for nasolacrimal duct obstruction

Background: TED (thyroid eye disease) is an inflammatory disease of the orbit caused by autoimmune diseases of the thyroid, which adversely affect the vision, appearance, and quality of life. Exophthalmos and eyelid retraction are the main features of TED, which can lead to ocular motility, diplopia, optic neuropathy, and permanent vision loss. The study aims to determine the most common clinical signs of TED in Mongolians and define whether there is a correlation with the levels of thyroid autoantibodies. Methods: The study involved 102 patients with TED and 81 patients with Graves’ ophthalmopathy. The clinical features of TED were identified and evaluated by activity score (CAS) and severity of GO using the European Group of Graves’ Orbitopathy (EUGOGO). Results: The mean age of TED patients was 42.6±11.2, which was younger than GD patients (P=0.012). The current smoker was 24 patients (23.5%) with TED, which is relatively higher than GD (P=0.0001). The most common ocular signs were eyelid retraction 80 (78.4%), proptosis 77 (75.5%), diplopia 14 (13.7%) and 4% vision loss. There were no differences in proptosis between the right (18 mm, median) and left eye (17.8 mm, median) (P>0.05). The mean CAS score was 3.09±1.72 and varied depending on gender and smoking. According to EUGOGO, 62.7% of the patients were moderately severe. Only 7 % of the patients were in the sight-threatening stage, presenting optic neuropathy and corneal breakdown. The mean TSI level in patients with TED was 37.95 ± 35.41 IU / ml, which was 2.7 times higher than the mean in patients with GD. Conclusions Eyelid retraction and exophthalmos are the most common clinical signs of TED. Early diagnosis of these features can prevent complications of the disease. Determining serum TSI levels will help in the treatment and monitoring of TED.