Abstract
Purpose :
Globe position within the bony orbit may be altered by orbital surgery involving bone removal. In orbital decompression surgery, after bone of the orbital wall(s) is removed, the periorbita is incised, inducing posterior globe displacement. In transorbital neurosurgery, bony osteotomies are created but the periorbita is left intact to minimize globe displacement. The aim of this project is to evaluate the impact of opening the periorbita on globe position following surgeries with orbital bone removal.
Methods :
A retrospective consecutive case review was performed. Subjects that underwent lateral wall orbital decompression with periorbita incised were compared with subjects who underwent transorbital neurologic surgery (TONES) bony osteotomies without periorbita incision, at a single academic center between 2016-2022. Pre and postoperative coherence tomography were analyzed using Horos (Purview; Annapolis, MD) with methods derived from Bingham et al. to approximate orbit bone volume by contouring cross-sectional areas from the inferior orbital fissure to the skull base in the axial plane. The volume of bone removed was calculated, as was the change in exophthalmometry. Two-tailed student’s t-test was used for statistical analysis.
Results :
In the orbital decompression group (N=5 orbits), the volume of bone removal was 0.54±0.4cm3 or a 4.3±7.5% reduction with a posterior globe displacement of 2.9±1.9mm. Comparatively, the TONES group (N=5 orbits) volume of bone removal was 2.98±1.5cm3 or a 31.0±10.7% reduction, with a posterior globe shift of 2.3±1.4mm. Two-sample t-test comparing globe displacement between the decompression and TONES subjects was not significantly different t(4)=0.86, p=0.41. Two sample t-tests comparing the bone volume removal and percent of volume removal between the two groups were significantly different t(4)=3.6, p=0.01 and t(4)=3.7, p=0.005 respectively.
Conclusions :
Although more bone was removed in the TONES group, relative globe position change was statistically insignificant between the two groups. Based on this finding, the authors infer that incision of the periorbita influences postoperative globe position. Given that periorbita incision techniques differ amongst surgeons, future analysis of the size, length, and shape of periorbita incision may provide insight into the degree of decompression and ultimate globe position.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.