Approach to the medial orbit is used in several circumstances, including repair of medial wall trauma, orbital decompression, and access to lacrimal sac or sino-nasal tumors with orbital involvement. When dissecting in the medial orbit, care should be taken to avoid damaging the medial canthal tendon, lacrimal canaliculi and sac, trochlea, superior oblique tendon and muscle, inferior oblique muscle, and the sensory nerves and vessels along the medial aspect of the superior orbital rim.
Tumors within or near the lacrimal sac or the frontal or ethmoid sinuses can be approached through a frontoethmoidal skin incision placed vertically just medial to the insertion of the medial canthal tendon. This route is generally used to enter the subperiosteal space by reflecting the medial canthal tendon in conjunction with the periosteum, thus preserving the lacrimal drainage apparatus.
An incision in the bulbar conjunctiva allows entry into the extraconal or sub-Tenon surgical space. If the medial rectus muscle is detached, the intraconal surgical space can be entered in the region of the anterior optic nerve for exploration or biopsy. If the posterior optic nerve or muscle cone needs to be accessed, a combined lateral/medial orbitotomy can be performed. A lateral orbitotomy with removal of the lateral orbital wall allows the globe to be displaced temporally, maximizing medial exposure to the deeper orbit.
This incision may be used for repair of medial wall fractures, for medial orbital bone decompression, and for drainage of medial subperiosteal abscesses. An incision posterior to the caruncle allows excellent exposure of the medial orbit (Fig 7-6). Blunt dissection is carried medially, followed by incision and elevation of the periosteum to gain access to the subperiosteal space. In addition, by combining the retrocaruncular incision with an inferior transconjunctival incision, panoramic exposure of the inferior and medial orbit is possible. The inferior oblique muscle may be divided at its origin along the inferomedial orbit rim and reattached at the end of surgery (Fig 7-7). This approach also provides better cosmesis than the traditional frontoethmoidal incision. However, to protect the canaliculi, care must be taken to remain posterior to the lacrimal drainage apparatus during dissection.
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.