distance between the superior aspect of the
optic canal and the base of the metoptic canal,
Optic strut connects the body of sphenoid to the inferomedial aspect of base of anterior clinoid process and is removed during anterior clinoidectomy and
optic canal decompression.
Indirect TON may be treated with various doses of steroids, or alternatively surgical
optic canal decompression can be performed (2,4,8,10).
At present, most scholars hold that the neurological symptoms are due to the thickening of the bone plate at the bottom of the skull and stenosis or occlusion of channels in which cranial nerves, spinal cord, and major blood vessels run, including the optic nerve compression caused by the
optic canal stenosis.[5] The mechanism of optic nerve damage is still not fully understood.
Megadose steroids should be withheld if more than 8 hours has elapsed since trauma, while
optic canal decompression plays no role if vision loss happened at the time of injury and not later, in addition to risk of intraoperative injury of optic nerve [1, 13].
Mizushima et al., "Intracranial penetrating injuries via the
optic canal," American Journal of Neuroradiology, vol.
The recommended imaging to analyze the sphenoid sinus and its surrounding structures is the CT paranasal sinuses including axial, coronal, sagittal, and sagittal oblique (parallel to the
optic canal) views.
A negative correlation between drusen diameter and RNFL thickness as well as greater RNFL loss in drusen located in the
optic canal have been demonstrated.
A soft-tissue enhancing mass extended into the
optic canal, causing compression and medial displacement of the right optic nerve (Figure 2A).
The optic nerve emerges from behind the eyeball and travels posteriorly towards the back of the orbit to enter the
optic canal. Along its path it can become compressed, inflamed, ischaemic or mechanically stretched by the abnormally enlarged surrounding extraocular muscles and orbital tissues leading to dysthyroid optic neuropathy (DON).
The infraorbital foramen was the landmark from which the distance between the following bony structures were examined; Nasion (NAS), Zygomatico maxillary suture (ZMS), Anterior nasal spine (ANS), and the distance between the inferior orbital rim (IOR) to
optic canal (OC), infraorbital foramen (IOF), inferior & superior orbital fissure (IF & SF) (Figure 1).