OBJECTIVE: To determine the accuracy of manual compass measurement and trigonometric determination of proptosis (MCMATDP).
METHODS: This agreement study included 120 eyes without eye diseases or injury of 60 patients who visited the ophthalmic clinic of Peking University Shenzhen Hospital from February 2020 to June 2020. The absolute values of proptosis were measured by MCMATDP and computed tomography (CT). The differences between the two methods were shown by Bland-Altman plot.
RESULTS: The cohort comprised 25 males and 35 females (average age 38.3 years). The absolute value of proptosis measured by CT was correlated with the MCMATDP. Further analysis showed that a 95% limit of agreement (LoA) was - 0.53 to 0.60 mm in the right eye and - 0.46 to 0.55 mm in the left eye between CT and MCMATDP. In addition, the 95% LoA was - 0.49 to 0.60 mm in both eyes between the two methods. All points were < 5% in Bland-Altman plots.
CONCLUSIONS: Compared to CT, MCMATDP is rather consistent in proptosis measurement. The new method is feasible in clinical practice when measuring proptosis. With the development of non-contact intelligent measurement software and the continuous improvement in measurement accuracy, a non-invasive, simple, and inexpensive measurement mode is true based on the theory of MCMATDP.

METHODS: This is a correlation study.
OBJECTIVE: The objective was to obtain normative values from modified Hertel exophthalmometer, to compare difference in values between modified and standard Hertel exophthalmometer and to statistically analyze for correlation.
METHODS: The study to validate the modification done to Hertel exophthalmometer was performed at the Department of Oral and Maxillofacial Surgery at our institute. Informed consent was obtained from patients; measurement in 100 volunteers was made with Hertel and modified Hertel exophthalmometer by a single observer, and the measurements taken by the 2 devices were tabulated along with variables such as age and gender. Data were collected and statistical analysis was performed to compare and correlate the values between standard and modified exophthalmometer. Differences of ocular protrusion values in gender and age were also calculated.
RESULTS: There has been no statistically significant difference in the normative data between standard Hertel and modified Hertel exophthalmometer and in relation to age and gender.
CONCLUSIONS: The modification of the Hertel exophthalmometer is validated and can also be used for relative exophthalmometry to assess the need for treatment and to evaluate the globe position and orbital volume intraoperatively. The proposed modification of the instrument allows it to be used in cases when one of the lateral orbital walls is fractured or displaced due to trauma.

OBJECTIVE: We propose a new method to analyze the feasibility of calculating proptosis on the basis of simple Pythagorean theorem.
METHODS: This is a non-inferiority trial, and the registration number is ChiCTR1900026490. The absolute value of proptosis of two eyes of patients without eye injury or diseases visiting our clinic from December 2017 to June 2019 was measured by computed tomography, Hertel exophthalmometer, and by simple Pythagorean theorem. With the application of MedCalc software version 19.0.4, the differences between these methods in two eyes were showed by Bland and Altman plot.
RESULTS: A 95% limit of agreement between computed tomography and Hertel exophthalmometer is -0.7 to 0.62 mm in right eye proptosis. A total of 4.44% (4/90) points were outside 95% limit of agreement. Similarly, the same method was used to compare the proptosis between computed tomography and other ways. We also compared the proptosis measured by homolateral and heterolateral simple Pythagorean theorem method in order to find out the consistence between them. The points in all Bland and Altman plots were lower than 5%, which means that the results of comparison between any two methods had a good consistency in the measurement of proptosis of both eyes.
CONCLUSIONS: Pythagorean theorem can be applied to evaluate proptosis and has a good consistency comparing with computed tomography and the Hertel exophthalmometer. The method can be used for measuring proptosis of unilateral orbital, maxillofacial trauma, and dysplasia accurately. It is practical in clinical use of proptosis assessment because of its accuracy, reliability, and simplicity.

OBJECTIVE: The aim of this study was to assess reproducibility of the repeated measurements from proposed computed exophthalmometry and to make a comparison with the Hertel exophthalmometer.
METHODS: Computed tomography scans of patients with pathological (group 1) and intact orbits (group 2) were included in this retrospective study. In both groups, a single investigator measured a difference of eyeballs\' protrusion using the proposed method of computed exophthalmometry. Briefly, the distances from the corneal apices of the left and right eyeballs to the line placed through the styloid processes of the temporal bones were measured and compared to each other three times independently.
RESULTS: In some patients with intact lateral orbital rims the results of computed exophthalmometry correlated with the measurements from the Hetrel exophthalmometer. The analysis of the triple measurements with computed exophthalmometry revealed no significant difference in the value of standard deviation of the results in patients with intact and pathological orbits. In comparison with the Hertel-type exophthalmometry, the proposed method demonstrated very low variability and high repeatability of the measurements. The difference of 0.10-0.87 mm in the eyeballs protrusion should be considered as normal. Computed exophthalmometry is an accurate and reproducible method, which can be used for the measurements of eyeballs\' protrusion.

OBJECTIVE: The aim of the present study was to assess normal eyeball protrusion from the orbital rim using two- and three-dimensional images and demonstrate the better suitability of CT images for assessment of exophthalmos.
METHODS: The facial computed tomographic (CT) images of Korean adults were acquired in sagittal and transverse views. The CT images were used in reconstructing three-dimensional volume of faces using computer software. The protrusion distances from orbital rims and the diameters of eyeballs were measured in the two views of the CT image and three-dimensional volume of the face. Relative exophthalmometry was calculated by the difference in protrusion distance between the right and left sides.
RESULTS: The eyeball protrusion was 4.9 and 12.5 mm in sagittal and transverse views, respectively. The protrusion distances were 2.9 mm in the three-dimensional volume of face. There were no significant differences between right and left sides in the degree of protrusion, and the difference was within 2 mm in more than 90% of the subjects.
CONCLUSIONS: The results of the present study will provide reliable criteria for precise diagnosis and postoperative monitoring using CT imaging of diseases such as thyroid-associated ophthalmopathy and orbital tumors.