F, An incision has been extended backward through the annular tendon between the superior and medial rectus muscles and through the optic sheath to expose the full length of the optic nerve. The trochlear nerve passes above the levator muscle at the orbital apex in its passage to the superior oblique muscle and should be protected in completing the incision through the annular tendon and along the optic sheath. This type of incision in the annular tendon can be combined with the medial supraorbital approach to provide access to the optic nerve from the optic chiasm to the globe. The sphenoid and ethmoidal sinuses are exposed on the medial side of the orbit. G, The levator and superior rectus muscles and the superior ophthalmic vein have been retracted medially to expose the intraorbital part of the optic nerve. The superior ophthalmic vein blocks the view of the deep apical area. H, The superior ophthalmic vein has been displaced laterally to expose the deep apical area. It blocks the view of the apical area, as shown in G, when it is retracted medially. I, The annular tendon has been divided between the origin of the lateral and superior rectus muscles, as can be performed in the lateral approach. The origin of the superior rectus muscle from the annular tendon has been retracted medially and the origin of the lateral rectus muscle has been retracted laterally. This incision can be combined with a lateral supraorbital approach to increase access to the structures in the superior orbital fissure. The nasociliary nerve crosses above the optic nerve in front of the annular tendon and orbital apex. The superior division of the oculomotor nerve sends branches into the lower surface of the superior rectus and levator muscle. The abducens nerve passes through the superior orbital fissure below the nasociliary nerve and enters the medial surface of the lateral rectus muscle. The ophthalmic artery courses on the lateral side of the optic nerve at the orbital apex. The sensory root to the ciliary ganglion arises from the nasociliary nerve and the motor parasympathetic root arises from the branch of the inferior division to the inferior oblique muscle. J, The levator and the frontal nerve are retracted medially, and the superior rectus muscle is retracted laterally. This exposes the middle third of the intraorbital portion of the optic nerve. It is the shortest route through the orbital roof to the optic nerve. The ophthalmic artery and the nasociliary nerve cross above the optic nerve. The branch of the superior division of the oculomotor nerve, which enters the lower surface of the superior rectus and levator muscles, crosses the field. K, A second variant of the central approach, in which the frontal nerve is retracted laterally with the superior rectus muscle. This approach provides a wider exposure of the optic nerve in the orbital apex than the exposure in which the branches of the frontal nerve are retracted medially with the levator muscle as shown in J. The site at which the medial and superior rectus muscles arise from the annular tendon is also exposed. (Images courtesy of AL Rhoton, Jr.)