The Optic Nerve

Abstract

The optic nerve is our most important cranial nerve. As it courses from the eyeball to the brain, it is divided into four segments: intraocular, intraorbital, intracanalicular, and intracranial. Four tests are primarily used to assess its functional integrity and detect optic nerve disorders. These tests are described along with key funduscopic findings. The clinical features of both common as well as notable disorders that occur along the four segments are presented. For example, papilledema and anterior ischemic optic neuropathy involve the intraocular segment, dysthyroid optic neuropathy or optic nerve sheath meningiomas affect the intraorbital segment, traumatic optic neuropathy is mainly within the intracanalicular segment, and pituitary tumors and suprasellar masses compromise the intracranial segment. Ancillary clinical symptoms and signs are highlighted that assist the neurologist in understanding and localizing each disorder along one of these segments. The chief means of confirming the diagnosis, often neuroimaging, are given, and common treatment modalities are provided.

Protective effects of human umbilical cord blood stem cell intravitreal transplantation against optic nerve injury in rats

“…RGC may die by apoptosis after traumatic optic nerve damage. In earlier reports, Fluorogold retrograde labeling has shown a good correlation with apoptosis as detected by TUNEL and/or caspase-3 methods [1,2,25]. Our experiment demonstrated an increase in RGC survival through grafted hUCBSCs.…”

“…Upon damage and shearing of RGCs following trauma, RGCs develop apoptosis, necrosis and degeneration. RGC regeneration after injury is limited, and may be due to multiple inhibitory effects which include neurotrophic factors, inflammatory cytokines and cells, and surrounding angiogenesis [2,14,15]. Previous studies were focused on drug treatment (all kinds of neuroprotection drugs), and surgical intervention (optic nerve decompression surgery).…”

“…down its progression, many individuals with TON still suffer an irreversible loss of vision [1,2]. Research is currently focused on developing new treatment strategies to rescue damaged photoreceptors and retinal ganglion cells (RGCs), and to replace lost cells through transplants.…”

The Maximum Tolerated Dose of Gamma Radiation to the Optic Nerve during Gamma Knife Radiosurgery in an Animal Study

“…Although gamma knife radiosurgery provides a much more effective noninvasive treatment for brain tumors, the tolerance dose of the visual apparatus should be considered when it is used to treat pituitary adenomas, especially tumors that are compressed or close to the optic apparatus [1,2,3,4,5]. In this study, we created optic nerve compression in cat models, which have similar neurobiological characteristics to optic nerves that are compressed by tumors in humans.…”

“…This procedure delivers a high dose of radiation in a single fraction and has a relatively sharp fall-off of radiation in the surrounding tissue; it therefore provides an effective, noninvasive treatment for brain tumors [2]. However, in pituitary adenomas, the proximity of the tumor to the optic nerves, chiasm and tracts increases the risk of visual complications [4]. Thus, it is important to consider the dose-response tolerance of the visual pathways when the gamma knife radiosurgery is used to treat pituitary adenomas.…”