BACKGROUND AND OBJECTIVES The transorbital approach varies by the extent of bony removal and the target. Orbital rim-sparing transorbital approach with removal of only the orbit's posterior wall provides optimal cosmetic results, without the need for reconstruction. The size of this corridor, limited by the medial globe retraction, has not yet been defined and is difficult to determine in cadavers because of postmortem tissue desiccation. By using patient-specific models in virtual reality, precise areas and degrees of surgical freedom (AOF and DOF, respectively) provided by globe retraction were calculated. These measurements define a potential maximum safe AOF and DOF, as well as the globe retraction, needed to achieve a sufficient surgical corridor. METHODS Using a virtual reality system, transorbital rim-preserving craniectomies were performed. The axial and sagittal DOF as well as AOF were calculated lateral to the globe, limited by the orbital rim and globe, with an anterior clinoid target. The DOFs and AOFs were calculated for each degree of medial globe retraction and analyzed using paired t tests. RESULTS With only 5 mm of retraction, the AOF was 886 mm2, while at 10 mm, the AOF was 1546 mm2. This increase between 5 and 10 mm allowed for the largest increase in surgical working corridor (P = .02). At 15 mm of retraction (previously studied point at which intraocular pressure raises), the AOF averaged 2189 mm2 and axial DOF averaged 23.1°. Eighteen DOF (a previously studied point needed to achieve sufficient working space for 2 instruments) was achieved at 11 mm on average, generating 1675 mm2 AOF. CONCLUSION Globe retraction of 11 mm is needed to achieve sufficient DOF for 2 surgical instruments, and 15 mm of retraction is a conservative limit that provides comparable AOFs with similar cranial approaches.

中文翻译：

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经眼眶手术走廊：眼球回缩的解剖学分析以及经眼睑眶缘保留内窥镜眼眶切开术 (TORPEDO) 方法的相关暴露。

背景和目标 经眶入路根据骨质去除的程度和目标而有所不同。保留眼眶边缘的经眼眶入路仅切除眼眶后壁，可提供最佳的美容效果，无需重建。该走廊的大小受到眼球内侧回缩的限制，尚未确定，并且由于死后组织干燥而很难在尸体中确定。通过在虚拟现实中使用患者特定模型，计算出由球体回缩提供的精确面积和手术自由度（分别为 AOF 和 DOF）。这些测量定义了实现足够的手术走廊所需的潜在最大安全 AOF 和 DOF，以及眼球回缩。方法 使用虚拟现实系统，进行经眼眶保留边缘的开颅手术。轴向和矢状 DOF 以及 AOF 是在地球侧面计算的，受眼眶边缘和地球限制，并具有前床突目标。计算每个内侧眼球回缩度的 DOF 和 AOF，并使用配对 t 检验进行分析。结果 仅缩回 5 mm 时，AOF 为 886 mm2，而缩回 10 mm 时，AOF 为 1546 mm2。5 至 10 毫米之间的增加使得手术工作走廊的增加最大（P = .02）。在回缩 15 毫米（之前研究的眼压升高点）时，AOF 平均为 2189 mm2，轴向 DOF 平均为 23.1°。平均 11 毫米实现了 18 个自由度（先前研究的点需要为 2 台仪器实现足够的工作空间），产生 1675 毫米 AOF。结论 需要 11 mm 的球形回缩才能为 2 个手术器械获得足够的 DOF，并且 15 mm 的回缩是一个保守的限制，可以通过类似的颅骨入路提供可比较的 AOF。