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Head and neck
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
This is the loss of vision without external or internal ophthalmoscopic evidence of eye injury – the optic atrophy appears weeks later and is usually said to be secondary to a direct globe injury, followed by retinal vascular occlusion, orbital compartment syndrome and injury to proximal neural structures. Treatment is usually conservative; the 1999 International Optic Nerve trauma study (Levin LA, Ophthalmology, 1999) demonstrated no clear benefit of high-dose steroids or optic canal decompression – there was an increase in acuity in 32%, 52% and 57% of surgery, steroid and observation groups, respectively, but it was non-randomised.
The eye and orbit
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
The orbit is four-sided and pyramidal in structure, housing the globe, optic nerve, the four rectus and two oblique muscles, the lacrimal gland, orbital fat, the cranial nerves III, IV, V and VI, the ophthalmic artery with its tributaries and the ophthalmic veins, which anastamose anteriorly with the face and posteriorly with the cranial cavity. Above is the frontal lobe of the brain, temporally the temporal fossa, inferiorly the maxillary sinus and nasally the lacrimal sac and ethmoidal and sphenoidal air sinuses. The optic nerve passes through the optic canal to the chiasm, with other nerves and vessels passing through the superior ophthalmic fissure.
Orbital trauma
Published in John Dudley Langdon, Mohan Francis Patel, Robert Andrew Ord, Peter Brennan, Operative Oral and Maxillofacial Surgery, 2017
At the orbital apex, the medially located optic canal passes through dense bone of the sphenoid bone transmitting the optic nerve together with the central artery of the retina. More laterally, the superior orbital fissure transmits branches of the ophthalmic division of the trigeminal nerve together with the third, fourth and sixth cranial nerves. The ‘superior orbital fissure syndrome’ comprises total ophthalmoplegia, upper lid ptosis and anaesthesia in the distribution of the ophthalmic division of the trigeminal nerve, ‘orbital apex syndrome’ includes these signs in conjunction with blindness. Within the orbit, the globe is supported by Lockwood’s suspensory ligament and moved by the extraocular muscles, it is enclosed in periorbital fat whose loss can contribute to enophthalmos. Anterior to the globe, the upper and lower tarsal plates are attached to the medial and lateral walls by the medial and lateral palprebal ligaments. This tense fascial sheath constitutes a ‘fifth wall’ of the orbital pyramid thereby forming a closed box. It is important to recognize this, for if orbital pressure increases following trauma, release of this fascial band by way of a lateral canthotomy can be sight saving, an important emergency surgical skill in the management of these injuries.
Current and emerging diagnostic and management approaches for idiopathic intracranial hypertension
Published in Expert Review of Neurotherapeutics, 2023
Ravi Piccus, Mark Thaller, Alexandra J Sinclair, Susan P Mollan
Neuroimaging also identifies characteristics of raised ICP such as partially or empty sella, enlarged optic nerve sheath complex, optic nerve tortuosity, globe flattening, optic nerve head protrusion and venous sinus stenosis [63,64]. Optic canal dimensions do not appear to influence papilledema grade as measured with CT imaging [65] and MRI findings have not been shown to occur at a higher frequency in those with worst visual outcomes [66]. Recent multivariate analysis of radiographic features indicated that a calculated caudate index, lateral ventricle index, and bilateral optic nerve tortuosity were significant predictors of IIH with an r2-value of 0.773 [67]. Other abnormalities with high specificity for the disease are posterior scleral flattening and perioptic subarachnoid space dilatation [68]. In clinical practice MRI findings of raised ICP incidentally found are raising concerns amongst physicians and in one study documented performing lumbar punctures (LP) and starting treatment without necessarily examining for papilledema first [69].
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2022
David A. Bellows, Noel C. Y. Chan, John J. Chen, Hui-Chen Cheng, Peter W. MacIntosh, Michael S. Vaphiades, Konrad P. Weber, Xiaojun Zhang
Among 92 patients with clinically diagnosed TED, 49 patients (98 orbits) were allocated to the TED-only group. DON was diagnosed in 43 patients, of which 76 orbits were allocated to the TED+DON group. Orbits of the unaffected eyes (10 orbits) in patients with unilateral DON were allocated to the TED+DON (unaffected) group. Forty orbits of 20 subjects were recruited as controls. Muscle volumes of each muscle were significantly higher in the TED+ON group than the TED alone group. However, the authors found that medial rectus (MR) muscle volume was the strongest predictor for the development of DON and they suggested patients with a MR muscle volume of >0.9 cm3 should be monitored more closely. This is most likely due to its close anatomical relationship with the optic nerve in the optic canal.
Clinical Evaluation and Treatment Outcome of Traumatic Optic Neuropathy in Nepal: A Retrospective Case Series
Published in Neuro-Ophthalmology, 2018
Sanjeeta Sitaula, Hira Nath Dahal, Ananda Kumar Sharma
Another way to classify TON is based on the site of injury. Intraocular optic nerve injury resulting from violent rotation of the globe leads to avulsion of the distal end of the optic nerve and usually assumes a typical fundus picture of peripapillary haemorrhage and disruption of the choroid. In the orbit, the nerve is redundant and is cushioned by orbital fat, hence the less chance of indirect injury. Trauma in this region is mainly due to intraorbital haemorrhage or emphysema causing either ischaemia or elevated intraorbital pressure compromising the circulation of optic nerve known as orbital compartmental syndrome. Intracanalicular injury is the most common site for TON and is associated with high-momentum decelerating injuries, especially in frontotemporal region. Optic nerve is strongly tethered to bone at the orbital opening of the optic canal, in the canal itself, and at the intracranial entrance of the canal. Moreover, the optic canal has a mean subdural cross-sectional space of only 1.84 mm2. Thus, even small amounts of bleeding or oedema may infarct the nerve and the fracture of canal may injure the nerve. At both ends of the canal, the nerve is also subjected to shearing forces, because the brain and orbital contents are free to move, but the intracanalicular portion of the nerve is not. The intracranial optic nerve is the next most common site of injury, followed by injuries that also involve the chiasm that produces characteristic visual field changes.19