There are 5 surgical spaces within the orbit (Fig 7-1):
the subperiosteal surgical space, which is the potential space between the bone and the periorbita (periosteum of the orbit)
the extraconal surgical space, which lies between the periorbita and the muscle cone
the sub-Tenon surgical space, which lies between the Tenon capsule and the globe
the subarachnoid surgical space, which lies between the optic nerve and the nerve sheath
the intraconal surgical space, which lies within the muscle cone
Figure 7-1 Surgical spaces of the orbit. A, Axial view. B, Coronal view.
(Illustration by Cyndie C. H. Wooley.)
Figure 7-2 Sites of surgical entry into the orbit. A, Curvilinear lateral orbitotomy. B, Eyelid crease lateral orbitotomy. C, Lateral canthotomy/cantholysis orbitotomy. D, Retrocaruncular medial orbitotomy. E, Frontoethmoidal medial orbitotomy. F, Upper eyelid crease anterior orbitotomy. G, Vertical eyelid split superomedial orbitotomy. H, Medial bulbar conjunctival orbitotomy. I, Subciliary inferior orbitotomy. J, Transconjunctival inferior orbitotomy. K, Lateral bulbar conjunctival orbitotomy.
(Illustration by Christine Gralapp, after a drawing by Jennifer Clemens.)
A single orbital lesion may involve more than 1 surgical space, and a combination of approaches may be necessary for pathologic processes affecting the orbit. An operating microscope is sometimes used, particularly for dissection inside the muscle cone. The approaches to these spaces—superior, inferior, medial, and lateral—are discussed in the following sections. Incisions used to reach these surgical spaces are shown in Figure 7-2.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.