A new method to determine proptosis and width of the palpebral rim

Purpose. The more common method to quantify interzigomatic distance and proptosis of the eye is the use of Hertel exophthalmometer. The eyelid width is usually determined using a ruler. These measurements are subjected to numerous variables and the reproducibility is very poor. The purpose of this work was the evaluation of a new computerized method useful to determine proptosis and width of the eyelid rim. Materials and methods. The study has been conducted on 20 patients with thyroid ophthalmopathy. Proptosis and interzigomatic distance have been measured with the use of an Hertel exophthalmometer, while the amplitude of the eyelid rim and lid retraction have been evaluated by a common ruler. Each measurement has been made by two different eye doctors. The same patients have been photographed from the front and the side by using similar conditions of illumination. The pictures underwent a computerized image analysis with a software developed in our Institute. The same examiners who made manual measurements evaluated ocular proptosis, interzigomatic distance, the width of eyelid rim, and the superior and inferior retraction of the lids using the computer. Results. Results of the measurements obtained by the two physicians with the Hertel exophthalmometer and with the ruler were significantly different. On the contrary, there was not significant difference between the data obtained with image analysis by the same examiners. Conclusions. The use of an appropriate software to carry out the image analysis to determine proptosis and width of the eyelid rim seems to be more accurate as compared to traditional methods. This is really important when the doctor needs to analyze the evolution of a clinical picture in the long run