Andy C. O. Cheng

Purpose: To describe the metric measurements and normal anatomic variants in Chinese bony orbits. Methods: Orbital osteology was studied in 194 orbits from 97 Chinese skulls. Morphologic observations and metric measurements were made to elucidate the variations of the orbital bony anatomy and to localize important fissures and foramina within the orbit. Sexual dimorphism and side asymmetry of orbital features were analyzed. Results were then compared with data from other populations. Results: The details of the orbital osteology in Chinese are described. Most orbital features show anatomic variations in terms of their existence, quantity, and location. Anatomic variants including quadruple and extrasutural posterior ethmoidal foramen are described for the first time. Side asymmetry and sexual dimorphism (male larger than female) are demonstrated in some orbital features. Compared with white and American populations, orbital measurements are generally smaller in Chinese, probably related to their smaller orbital size. Conclusions: The Chinese orbital osteology demonstrates considerable variability. The newly described anatomic variants found on the posterior ethmoidal foramen may affect surgical procedures related to the medial orbital wall. Sexual dimorphism and ethnic variations of the orbital bony anatomy may affect surgical approach to orbital diseases in different populations.

We report the outcome in 2 eyes of 2 patients with retained silicone oil droplets in the anterior chamber drainage angle after the use of an ophthalmic viscosurgical device (OVD) during cataract surgery. Silicone oil droplets were observed when the OVD was injected into the anterior chamber during phacoemulsification. Despite removal by irrigation and aspiration, droplets were observed in the anterior chamber during the immediate postoperative period. At 15 months, they were observed in the drainage angle. The retained silicone did not produce untoward side effects in the eyes. Silicone oil is a common contaminant in OVDs but appears to be inert and harmless when retained in small amounts in the anterior chamber drainage angle.

To elucidate the characteristics and location of the supraorbital and frontal exits of the supraorbital nerve in Chinese skulls and to compare these findings with other ethnic populations. The anatomy of the supraorbital nerve exits was studied in 97 adult Chinese skulls (194 orbits). The characteristics and location of the supraorbital nerve exits were determined. Analyses were performed to compare differences between sexes and sides. Data were then compared with those of the other populations. Supraorbital exits were found in all 194 orbits. Among these, 89 (45.9%) were foramina. Frontal exits were found in 69 of the 194 (35.6%) orbits in which 18 were foramina (9.3%). The location of the supraorbital exits showed a skewed distribution toward the medial aspect of the superior orbital rim. The median distance between the supraorbital exits and the facial midline was 24.56 mm. Eighty percent of the supraorbital exits lay between 20.77 mm and 30.52 mm from the facial midline. The mean frontal exit was 7.02 mm medial to the supraorbital exits. Compared with other populations, a higher proportion of Chinese have foramina above the superior orbital rim as the exits for the supraorbital neurovascular bundle. The location of the supraorbital nerve exit is highly variable in all studied populations. In a significant proportion of Chinese, the supraorbital nerve exits are located toward the medial aspect of and above the superior orbital rim. Extra care should be taken during dissection around this region to avoid damage to the supraorbital nerve.