Location of the Optic Foramen Relative to the Sphenoid Sinus and Orbital Apex Structures

Abstract

Background: Orbital decompression is performed to reduce intraorbital pressure by removing the fat tissue and bone around the orbit. Access to proper equipment, experienced personnel, and adequate anatomical knowledge are essential to perform this procedure. To achieve maximum decompression, surgeons need to open the orbit up to the apex, including the optic foramen and the annulus of Zinn. Objectives: This study aimed to determine the location of the sphenoid sinus relative to the optic foramen using CT scan, which is essential for orbital decompression surgery, in the Central Anatolia Region, Turkey. Patients and Methods: This cross-sectional study was conducted on 64 patients from the Turkish population between March 15 and April 15, 2021 in the Central Anatolia Region. The patients were selected using the purposive sampling method. Based on the cranial CT scans, a total of 128 orbits were evaluated using the hospital’s picture archiving and communication system. Patients included in this study were admitted to the hospital with headache. However, their CT images, evaluated by an experienced radiologist, were reported to be normal. The relationship between the optic foramen and the anterior surface of the sphenoid sinus was examined, and the location of the optic foramen was determined as anterior, posterior, or equal to the sphenoid sinus. Descriptive statistics were measured for statistical analysis. Results: The participants of this study included 32 men and 32 women in the age range of 20 - 67 years. Based on the analyses, the optic foramen was mainly opposite to the anterior aspect of the sphenoid sinus in both females and males; this finding was more prominent in females. In the right orbit, the mean distance of the optic foramen to the anterior surface of the sphenoid sinus was +6.97 mm if the optic foramen was anterior to the anterior surface of the sphenoid sinus, while it was -4.1 mm if the optic foramen was located posteriorly to the anterior surface of the sphenoid sinus. Similarly, in the left orbit, the mean distance of the optic foramen to the anterior surface of the sphenoid sinus was +6.97 mm if the optic foramen was located anteriorly, while it was -4.15 mm if the optic foramen was located posteriorly to the anterior surface of the sphenoid sinus. The position of the optic foramen was symmetrical in 60.9% of cases in the two orbits. Conclusions: Based on the results of CT scan, the optic foramen was mainly located opposite to the anterior aspect of the sphenoid sinus; this finding was more frequently observed in females (59.4%) than in males (40.6%). The present results can provide further information for surgeons to perform orbital decompression or surgeries posterior to the orbit.