Effects of Lateral Orbital Rim Resection on Intraorbital Pressure in Endoscopic Trans-Orbital Approaches

Overview

This cadaveric study evaluated the impact of lateral orbital rim (LOR) removal on intraorbital pressure (IORP) during endoscopic transorbital approaches (ETOA). Findings indicate that LOR removal may reduce orbital pressure increases associated with orbital retraction, potentially expanding the surgical corridor and minimizing pressure-related complications.

Background

Endoscopic transorbital approaches (ETOA) provide access to the ventral skull base but require orbital retraction, which can increase intraocular and intraorbital pressures. Elevated pressures beyond physiological ranges (7–21 mmHg) risk optic nerve hypoperfusion and retinal damage. Retraction depths exceeding 1.5 cm from the orbital rim significantly raise intraocular pressure. LOR removal has been proposed to increase working space, but its effect on intraorbital pressure was previously unknown.

Data Highlights

Key Findings

• Intraorbital pressure (IORP) increases proportionally with orbital retraction depth during ETOA.
• Retraction beyond 1.5 cm from the lateral orbital rim causes dangerous elevations in IORP.
• LOR removal significantly expands the surgical corridor and reduces the magnitude of IORP elevation during the procedure.
• Use of a solid-state strain-gauge microtransducer allows accurate real-time measurement of intraorbital pressure in cadaveric models.
• Bone removal volume was quantified via pre- and post-procedure CT scans, confirming the extent of lateral orbital rim resection.

Clinical Implications

Removing the lateral orbital rim at the start of ETOA may mitigate the increase in intraorbital pressure caused by orbital retraction, potentially reducing the risk of pressure-related complications such as optic nerve hypoperfusion. Surgeons should consider LOR removal to enhance the working space and improve safety during transorbital skull base surgeries.

Conclusion

Lateral orbital rim resection during endoscopic transorbital approaches effectively decreases intraorbital pressure elevations associated with orbital retraction, thereby expanding the surgical corridor and potentially reducing orbital complications. This technique represents a valuable modification to improve procedural safety.

References

1. Kim et al. 2013 -- Relationship Between Orbital Retraction and Intraocular Pressure
2. Laval University Neurosurgical Innovation Laboratory Study -- Effects of LOR Resection on IORP
3. Codman Microsensor® ICP Transducer Technical Data