An optic pit is a depression of the optic disc surface that is often gray or white, located inferotemporally, and associated with a mild visual field defect (usually paracentral or arcuate). Serous detachment of the macula develops in 25%–75% of cases, possibly related to liquefied vitreous entering the subretinal space through communication between the optic pit and the macula.

Colobomas of the nerve result from incomplete closure of the embryonic fissure and usually occur inferiorly; they occasionally extend to the adjacent choroid and retina. Visual field defects and an RAPD can occur depending on the degree of abnormality. Colobomas of other structures, such as iris and choroid, may be present.

The dysplastic nerve of papillorenal syndrome or renal coloboma syndrome appears excavated with absence or attenuation of the central retinal vessels and multiple cilioretinal vessels emanating and exiting from the disc edge. Visual acuity is often normal, but perimetry may reflect superonasal visual field defects. Controversy exists whether the nerves are colobomatous from incomplete embryonic fissure closure or from a primary dysplasia of the optic nerve. This characteristic optic nerve appearance may indicate renal failure secondary to renal hypoplasia and is linked to mutations in the PAX2 gene (which are autosomal dominant).

The morning glory disc anomaly is a funnel-shaped staphylomatous excavation of the optic nerve and peripapillary retina. It is more common in females and most often unilateral. The disc is enlarged, pink or orange, and either elevated or recessed within the staphyloma. Chorioretinal pigmentation surrounds the excavation, and white glial tissue is present on the central disc surface. The characteristic feature is the emanation of retinal vessels from the periphery of the disc. Visual acuity can be normal but is often 20/200 or worse and accompanied by an RAPD. Nonrhegmatogenous serous retinal detachments occur in 26%–38% of cases. Neuroimaging is warranted to evaluate for a basal encephalocele and CNS vascular anomalies.

Lee BJ, Traboulsi EI. Update on the morning glory disc anomaly. Ophthalmic Genet. 2008;29(2):47–52. Nicholson B, Ahmad B, Sears JE. Congenital optic nerve malformations. Int Ophthalmol Clin. 2011;51(1):49–76.

Posterior Optic Neuropathies

Retrobulbar optic neuritis

Optic neuritis typically occurs in young (mean age, 32 years), female (77%) patients, and it presents as subacute monocular visual loss that develops over several days. Periorbital pain, particularly with eye movement, occurs in 92% of cases and often precedes vision loss. The retrobulbar form (in which the optic disc appears normal) occurs in 65% of cases. Unless the optic neuritis is bilateral and symmetric, an RAPD is also present. Perimetry testing most often shows generalized reduction of sensitivity (48%), and any pattern of visual field loss may appear (Fig 4-19). Dyschromatopsia, particularly for red, is nearly universal and is often out of proportion to the visual acuity loss. Optic neuritis shows some improvement within 1 month in the vast majority of cases.

Figure 4-19 A, Disc photograph in retrobulbar optic neuritis, showing normal appearance. B, A central scotoma is shown on automated perimetry results. C, T1-weighted axial MRI scan of the orbits with fat-suppression and gadolinium administration, showing enhancement of the right intraorbital optic nerve (arrow). D, T2-weighted axial MRI scan of the brain, demonstrating multiple white matter hyperintensities (arrows) consistent with demyelination. (Parts A, B courtesy of

Steven A. Newman, MD; part C courtesy of Michael S. Lee, MD; part D courtesy of Anthony C. Arnold, MD.)

Most cases of optic neuritis represent isolated or demyelinating disorders and do not require further workup for another diagnosis. Atypical features that should prompt further evaluation include lack of pain, protracted pain or vision loss, significant swelling of the optic disc, inflammatory ocular features (eg, uveitis, phlebitis, choroiditis, pars planitis), bilateral vision loss, involvement of other cranial nerves, steroid-responsive optic neuropathy, or lack of any vision recovery by 1 month. Additional hematologic, serologic, and other testing may be of value. Such studies may include the following:

serum and CSF rapid plasma reagin and fluorescent treponemal antibody absorption testing (for syphilis)

chest x-ray, gallium scan, serum angiotensin-converting enzyme testing (for sarcoidosis)

ESR determination, antinuclear antibody testing, and anti-DNA antibody testing (for systemic lupus erythematosus or vasculitis)

serum neuromyelitis optica IgG testing and spinal MRI (for neuromyelitis)

brain and orbit MRI with gadolinium contrast (for compressive, infiltrative disorders) testing of antibody titers for Lyme disease (if endemic)

Leber hereditary optic neuropathy testing

serum Quantiferon Gold testing or purified protein derivative skin test (for tuberculosis)

The ONTT 10-year follow-up study reported that optic neuritis recurred in the affected or fellow eye in 35% of cases overall and in 48% of patients with conversion to MS. Most eyes with a recurrence regained normal or almost-normal vision. After 15 years of follow-up in the ONTT, 92% of patients with optic neuritis had recovery of visual acuity to 20/40 or better; 3% had final visual acuities of 20/200 or worse. Despite their seemingly excellent prognosis, patients with optic neuritis usually remain aware of visual deficits in the affected eye after recovery. Studies using measures of visual function other than Snellen visual acuity (eg, contrast sensitivity, motion detection, stereopsis) show residual abnormalities in up to 90% of patients with at least 20/30 visual acuity.

In the absence of a known diagnosis of MS, MRI of the brain is recommended in every case of retrobulbar neuritis. The evaluation for periventricular white matter lesions consistent with demyelination is the single best test for assessing the risk of future MS and to guide subsequent decisions on the use of immunomodulation therapy (see the following section). The 15-year data from the ONTT demonstrate a risk for MS of 25% for patients with zero lesions on MRI versus 72% for patients with at least 1 lesion, with the highest rate of conversion within the first 5 years. Patients with normal MRI results and no conversion to MS by year 10 had only a 2% risk of conversion by year 15 (see Chapter 14). Among patients with normal baseline MRI results, a lower risk of future MS was associated with male sex, optic disc swelling, and atypical features of optic neuritis (absence of pain, no light perception vision, peripapillary hemorrhages, and retinal exudates).

Treatment of optic neuritis The ONTT demonstrated that corticosteroid therapy for optic neuritis had no long-term beneficial effect on vision, although the use of intravenous methylprednisolone, 250 mg every 6 hours for 3 days, followed by oral prednisone, 1 mg/kg/day for 11 days, sped recovery by 1–2 weeks. Patients receiving oral prednisone alone did not have any benefit to vision and incurred a recurrence rate double that of the other groups; therefore, this treatment is not recommended. Intravenous therapy demonstrated a reduction in the rate of development of clinically definite MS after the initial optic neuritis only in the subgroup of patients with MRI scans showing 2 or more white matter lesions. At 2 years, these patients’ risk for MS was 36% untreated, 16% treated. By follow-up year 3 and thereafter, however, this protective effect was lost.

With unclear benefits, the value of therapy and of additional diagnostic evaluation for MS must be assessed individually. In cases in which a rapid return of vision is essential (eg, monocular patient, patient with an occupational need), intravenous methylprednisolone on an outpatient basis may be considered; otherwise, treatment for vision recovery is not required. An MRI scan is generally performed to assess MS risk, but additional evaluation, including CSF analysis, is probably best referred to a consulting neurologist. The value of intravenous corticosteroids alone to reduce the long-term risk of MS is unproven.

Immunomodulatory therapy is of proven benefit for reducing morbidity in the relapsing-remitting form of MS, and studies have shown that such drugs delay the conversion of patients with acute optic neuritis or other clinically isolated syndrome with high-risk MRI characteristics to definite MS (see Chapter 14 for a discussion of MS treatment.)

Beck RW, Cleary PA, Anderson MM Jr, et al. A randomized, controlled trial of corticosteroids in the treatment of acute optic neuritis. The Optic Neuritis Study Group. N Engl J Med. 1992;326(9):581–588.

Optic Neuritis Study Group. Multiple sclerosis risk after optic neuritis: final optic neuritis treatment trial follow-up. Arch Neurol. 2008;65(6):727–732.

Optic Neuritis Study Group. Visual function 15 years after optic neuritis: a final follow-up report from the optic neuritis treatment trial. Ophthalmology. 2008;115(6):1079–1082 e5. Epub 2007 Nov 5.

Neuromyelitis optica

Optic neuritis and acute myelitis characterize neuromyelitis optica (NMO), also known as Devic syndrome. The diagnostic criteria for NMO include the following:

optic neuritis (unilateral or bilateral) myelitis

at least 2 of the following:

a contiguous spinal cord lesion on MRI involving 3 or more vertebral segments

a brain MRI scan nondiagnostic for MS a positive NMO-IgG serologic test result

These criteria provide 99% sensitivity and 90% specificity. The criterion for NMO-IgG autoantibody alone has 76% sensitivity and 94% specificity; this autoantibody binds to aquaporin-4, the principal water channel protein expressed in astroglial foot processes that are involved in fluid homeostasis in the CNS. The vision and neurologic prognoses in NMO are poorer than in MS. Although many patients experience myelitis and optic neuritis within weeks to months of each other, the episodes may be separated by several years. Testing for NMO-IgG should be considered for patients with optic neuritis in the following scenarios: progressive vision loss for more than 2 weeks, lack of vision improvement by 1 month, and recurrent optic neuritis. In NMO, the episodes of vision loss tend to recur, with severe visual impairment (<20/200) common in at least 1 eye. The mainstay of treatment during the acute period remains high-dose intravenous corticosteroids. For poorly responsive NMO, administration of intravenous immunoglobulin or plasmapheresis can be considered. Use of other immunosuppressive drugs such as azathioprine, mycophenolate, and rituximab can reduce the risk of relapse.

Papais-Alvarenga RM, Carellos C, Alvarenga MP, Holander C, Bichara RP, Thuler LC. Clinical course of optic neuritis in patients with relapsing neuromyelitis optica. Arch Ophthalmol. 2008;126(1):12–16.

Wingerchuk DM, Lennon VA, Pittock SJ, Lucchinetti CF, Weinshenker BG. Revised diagnostic criteria for neuromyelitis optica. Neurology. 2006;66(10):1485–1489.

Optic perineuritis

Optic perineuritis is inflammation of the optic nerve sheath. Similarities between optic neuritis and optic perineuritis include acute painful vision loss and a female predilection. However, patients are generally older (36% are >50 years), vision loss progresses over several weeks, and pain persists until treated. Orbital MRI scans show enhancement of the dural sheath rather than the optic nerve

itself. Although the neuroimaging results can appear similar to those of optic nerve sheath meningioma, pain helps differentiate the 2 conditions. Distinguishing optic perineuritis from optic neuritis is important with respect to not only treatment but also prognosis for the development of MS. Patients with optic perineuritis respond immediately and dramatically to corticosteroid treatment, but relapses are common with short courses of treatment. Without treatment, patients incur progressive loss of vision. Optic perineuritis is not associated with an increased risk of demyelinating disease.

Purvin V, Kawasaki A, Jacobson DM. Optic perineuritis: clinical and radiographic features. Arch Ophthalmol. 2001;119(9):1299–1306.

Thyroid eye disease

Thyroid eye disease (TED) can present with progressive enlargement of extraocular muscles or orbital fat hypertrophy. In rare cases, progressive proptosis can stretch the optic nerve and cause dysfunction. The extraocular muscles can also enlarge to an extent that they compress the optic nerve at the orbital apex (Fig 4-20). Patients usually present with associated signs (eg, eyelid retraction and lag) and may show signs of orbital congestion (eg, eyelid and conjunctival edema) in addition to proptosis. However, some patients demonstrate only minimal orbital findings.

Figure 4-20 Thyroid eye disease in a 48-year-old man with a 6-month history of weakness, gradual swelling around the eyes, and progressively decreased visual acuity over the prior month. Visual acuity was 20/200 OD and 20/80 OS, with a mild right afferent pupillary defect. A, B, Automated perimetry testing shows bilateral central and inferior visual field loss. Axial (C) and coronal (D) CT scans show the optic nerve becoming encroached upon (arrow in C) by enlarged extraocular muscles. Enlargement of extraocular muscle in thyroid eye disease typically spares the muscle tendon. (Parts A, B courtesy

of Steven A. Newman, MD; parts C, D courtesy of Michael S. Lee, MD.)

The vision loss associated with TED is usually slowly progressive, insidious, and most often bilateral. Dyschromatopsia may be an early sign of optic neuropathy. Visual field testing results show central or diffuse depression, and an RAPD is present when the optic neuropathy is asymmetric or unilateral. The optic disc is commonly normal but may be edematous. Optic atrophy may be present in chronic cases.

Use of systemic steroids in the acute phase reduces compression on the optic nerve. This approach generally acts as a temporizing measure until surgical decompression of the posterior orbit is performed. Radiation therapy is not indicated for acute optic neuropathy. TED is discussed at

greater length in Chapter 14 and in BCSC Section 7, Orbit, Eyelids, and Lacrimal System.

Intraorbital or intracanalicular compressive optic neuropathy

Patients with intraorbital or intracanalicular compressive lesions typically present with slowly progressive vision loss, an RAPD, and monocular visual field loss (usually central or diffuse). There may be subtle associated signs of orbital disease such as eyelid edema, retraction, or lag; ptosis; proptosis; or ophthalmoplegia. The optic disc may be normal or mildly atrophic at presentation, although anterior orbital lesions may produce optic disc edema. Optociliary shunt vessels (retinochoroidal collaterals) or choroidal folds may also be present. The lesions that most commonly produce optic neuropathy include optic nerve sheath meningioma and glioma. Cavernous hemangioma, although common in the orbit, produces compressive optic neuropathy only occasionally.

If an orbital compressive lesion is suspected, neuroimaging is indicated. Although MRI is best for evaluating soft-tissue abnormalities in the orbit, particularly in differentiating meningioma from glioma, a thin-section CT scan remains a highly satisfactory option and is preferred for evaluation of calcification and bony abnormalities.

Optic nerve sheath meningioma Optic nerve sheath meningioma (ONSM) arises from proliferations of the meningoepithelial cells lining the sheath of the intraorbital or intracanalicular optic nerve (Fig 4-21; see also Chapter 2, Fig 2-7). Although these tumors are uncommon (1%–2% of all meningiomas), they account for one-third of primary optic nerve tumors, second only to optic nerve glioma. They are usually detected in adults aged 40–50 years and affect women 3 times as often as men; 4%–7% of optic nerve sheath meningiomas occur in children. Patients may present with the classic diagnostic triad:

1.painless, slowly progressive monocular vision loss (see Chapter 2, Fig 2-16)

2.optic atrophy

3.optociliary shunt vessels

Fractionated radiation therapy is the treatment of choice for ONSM and has been reported to produce stability or vision improvement in up to 94.3% of patients. However, it remains unclear whether radiation should be administered immediately upon diagnosis or when tumor growth or progressive vision loss is documented because patients with ONSM may have minimal loss of vision for several years. Radiation retinopathy and pituitary dysfunction are reported as late radiation complications.

Surgery for biopsy or excision is typically ill-advised because the potential for significant vision loss is considerable. However, if the tumor extends intracranially or, in very rare cases, across the planum sphenoidale, the risk of contralateral vision loss may warrant surgical excision, particularly when severe ipsilateral vision loss is present. Observation is considered appropriate by many if there is no change in visual function or tumor size. Optic nerve sheath meningiomas in children may be more aggressive, with more rapid vision loss and more frequent recurrence after therapy. Therefore, children must be monitored with increased frequency and decisions made accordingly.

Andrews DW, Foroozan R, Yang BP, et al. Fractionated stereotactic radiotherapy for the treatment of optic nerve sheath meningiomas: preliminary observations of 33 optic nerves in 30 patients with historical comparison to observation with or without prior surgery. Neurosurgery. 2002;51(4):890–904.

Arnold AC. Optic nerve meningioma. Focal Points. Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2004, module 7.

Dutton JJ. Optic nerve sheath meningiomas. Surv Ophthalmol. 1992;37(3):167–183.

Miller NR. New concepts in the diagnosis and management of optic nerve sheath meningioma. J Neuroophthalmol. 2006;26(3):200–208.

Turbin RE, Thompson CR, Kennerdell JS, Cockerham KP, Kupersmith MJ. A long-term visual outcome comparison in patients with optic nerve sheath meningioma managed with observation, surgery, radiotherapy, or surgery and radiotherapy. Ophthalmology. 2002;109(5):890–900.

Optic pathway glioma Although optic pathway gliomas (OPGs, or pilocytic astrocytomas) are generally uncommon (accounting for only about 1% of intracranial tumors), they are the most common primary tumor of the optic nerve. They may involve the optic nerve, the chiasm, or both (Fig 4-22).

Figure 4-22 A, Axial contrast-enhanced orbital CT scan shows a right optic nerve glioma. The optic nerve is enlarged and kinked and demonstrates mild hypodense cystic change centrally. The tumor extends intracranially. B, Axial T2-weighted MRI scan (non–contrast-enhanced) of the orbits shows an enlarged, hyperintense, globular glioma of the right optic nerve. C, Coronal T1-weighted MRI scan shows prominent enlargement at the junction of the optic nerves and chiasm.

Approximately 70% of OPGs are detected during the first decade of life and 90%, by the second; however, they may occur at any age. There is no definite sex predilection. The most common presenting findings are proptosis (94%), vision loss (87.5%), optic disc pallor (59%), disc edema (35%), and strabismus (27%). Patients infrequently present with asymptomatic isolated optic atrophy. An RAPD is usually present in unilateral or asymmetric cases, along with a typical optic nerve– related visual field defect (if the patient is cooperative enough for visual field testing). Retinochoroidal collaterals may be present on the affected disc, although they are observed less commonly than with meningiomas. Diagnosis is confirmed by neuroradiologic findings (see Table 4- 6).

The association of OPG to neurofibromatosis type 1 (NF1) is incompletely understood. In patients with NF1, the incidence of OPG is 7.8%–21%; in patients with OPG, the incidence of NF1 is 10%– 70%. The wide variance probably relates to referral bias, differences in neuroimaging detection rates, and criteria for diagnosis. Similarly, the relationship between NF1 and the behavior of the glioma is unclear. Several investigators suggest that optic nerve gliomas in patients with NF1 have a

more benign prognosis, but this issue is unresolved. Neurofibromatosis is discussed in greater depth in Chapter 14.

As with optic nerve sheath meningiomas, biopsy of the mass is generally not required because

the advent of high-resolution neuroimaging has improved diagnostic accuracy

biopsy of the sheath alone may be inaccurate, with reactive meningeal hyperplasia in gliomas falsely suggesting meningioma

biopsy of the optic nerve substance may cause additional vision loss

the histologic appearance of the tumor is not necessarily predictive of biological behavior

OPG involving the chiasm may show bitemporal or bilateral optic nerve–related visual field defects. Involvement of the chiasm may produce see-saw nystagmus or a monocular shimmering nystagmoid oscillation (pseudo–spasmus nutans). Large tumors may cause obstructive hydrocephalus with elevated ICP, headache, and papilledema. Involvement of the hypothalamus may result in precocious puberty or the diencephalic syndrome. Occasionally, surgery may relieve external compression on the chiasm, but otherwise surgical excision of the tumor is not indicated. Hydrocephalus may require surgical shunting.

There is no universally accepted management for OPG. Observation is indicated for patients with relatively good vision and stable radiographic appearance. Most patients show stability or very slow progression over years and sometimes show spontaneous regression. Chemotherapy is emerging as initial treatment for patients with severe vision loss at presentation or evidence of progression. Combination therapy with carboplatin and vincristine is the most accepted regimen, but other chemotherapeutic drugs are used as well. Radiotherapy is controversial because of inconclusive results and potential complications, including panhypopituitarism and cognitive disabilities. Fractionated stereotactic radiotherapy was used successfully for optic nerve gliomas in 1 study without secondary adverse effects after a median follow-up period of 97 months. Surgical excision may be indicated in patients with severe vision loss associated with disfiguring proptosis. Surgery has been advocated to prevent advancement into the chiasm; however, extension to the chiasm is rare.

Malignant astrocytomas are rare neoplasms involving the anterior visual pathway that almost always occur in adulthood. The mean age is in the 60s, and there is no sex predilection. Patients present with acute onset pain and either unilateral or bilateral vision loss. With unilateral lesions, the second eye invariably becomes involved within weeks. The optic disc appears normal or pale at presentation in most cases, but disc edema and retinal obstruction can also occur.

An MRI scan most often shows diffuse intrinsic enlargement and enhancement of the affected optic nerves, chiasm, and optic tracts, with inhomogeneity due to cystic spaces within the tumor. Occasionally, a large exophytic component may encroach on the suprasellar cistern. Histologically, malignant optic nerve gliomas are classified as anaplastic astrocytomas or glioblastoma multiforme.

Vision loss is severe and rapidly progressive. Treatment is rarely successful, although radiotherapy and chemotherapy have been attempted, with blindness usually developing 2–4 months after onset of vision loss. The tumor is aggressively infiltrative, and death from hypothalamic and brainstem involvement usually occurs within 6–12 months.

Lee AG. Neuroophthalmological management of optic pathway gliomas. Neurosurg Focus. 2007;23(5):E1.

Listernick R, Ferner RE, Liu GT, Gutmann DH. Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations. Ann Neurol. 2007;61(3):189–198.

Matloob S, Fan JC, Danesh-Meyer HV. Multifocal malignant optic glioma of adulthood presenting as acute anterior optic neuropathy. J Clin Neurosci. 2011;18(7):974–977. Epub 2011 May 6.

without an afferent pupillary defect. A, B, Visual field results demonstrate a cecocentral scotoma on the left and a relative central scotoma on the right. C, D, Fundus appearance shows mild temporal optic atrophy OU, with papillomacular nerve fiber layer dropout. After treatment with multivitamins and hydroxycobalamin injections, field defects resolved completely and visual acuity returned to 20/20. (Courtesy of Steven A. Newman, MD.)

Diagnosis requires a careful history for possible medication or other toxic exposure, substance abuse, or dietary deficiency. The most commonly implicated medications include ethambutol, linezolid, isoniazid, chloramphenicol, hydroxyquinolines, penicillamine, and the antineoplastic drugs cisplatin and vincristine (Table 4-7). Lead ingestion in children may also result in optic neuropathy. Ethanol abuse probably is associated indirectly with optic neuropathy in that it may contribute to malnutrition. Dietary deficiencies of vitamin B12, folate, and thiamine may cause optic neuropathy, but exact deficiencies are difficult to identify in cases of suspected nutritional optic neuropathy. Tobacco use has long been implicated in optic nerve dysfunction, but the evidence is questionable.

Table 4-7

Establishing the diagnosis may be difficult, particularly for patients with vague complaints and little objective abnormality. A careful and detailed dietary history may help, but ethanol abusers may obscure or falsify details of food and ethanol ingestion. Specific vitamin deficiencies are detected only infrequently on blood testing. It may be challenging to implicate a specific medication in patients using multiple medications.

The differential diagnosis includes subtle maculopathies and hereditary, compressive, demyelinating, and infiltrative optic neuropathies. Fluorescein angiographic studies, screening hematologic and serologic testing, and CSF analysis (in rare cases) are performed in questionable cases. Neuroimaging should be performed routinely to rule out a compressive etiology.

Treatment is directed at reversal of the inciting cause: stopping medication or substance abuse and replacement of dietary deficiencies. Prognosis for vision recovery is good if optic atrophy has not supervened; however, recovery is highly variable. Recovery of vision typically occurs slowly over several months.

Melamud A, Kosmorsky GS, Lee MS. Ocular ethambutol toxicity. Mayo Clin Proc. 2003;78(11):1409–1411.

Orssaud C, Roche O, Dufier JL. Nutritional optic neuropathies. J Neurol Sci. 2007;262(1–2):158–164. Epub 2007 Aug 17. Rucker JC, Hamilton SR, Bardenstein D, Isada CM, Lee MS. Linezolid-associated toxic optic neuropathy. Neurology.

2006;66(4):595–598.

Traumatic optic neuropathy

The optic nerve may be damaged by trauma to the head, orbit, or globe. Direct traumatic optic neuropathy results from avulsion of the nerve itself or from laceration by bone fragments (Fig 4-24)

or other foreign bodies. Injuries may also produce compressive optic neuropathy secondary to intraorbital or intrasheath hemorrhage. Indirect trauma is the most common form and is discussed further here. Indirect traumatic optic neuropathy (without direct nerve trauma) may occur with even relatively minor head injury. The trauma involves the frontal or maxillary bone, and the transmitted forces damage the optic nerve at the orbital apex. The pathophysiology presumably involves shear forces on the nerve and possibly its vascular supply at its intracanalicular tether point. Vision loss is typically immediate and often severe (24%–86% of patients have no light perception at presentation). External evidence of injury may be scarce. An afferent defect is invariably present. Although the optic disc usually appears normal at onset, it becomes atrophic within 4–8 weeks.

Figure 4-24 CT scan of an 18-year-old involved in a severe motor vehicle accident. He had noted decreased visual acuity on the left side. The CT scan shows fracture in the area of the left optic canal, with a bone fragment (arrow) impinging on the left optic nerve. Visual acuity improved after transethmoidal decompression of the canal. (Courtesy of Steven A. Newman,

MD.)

Management of suspected optic nerve injury requires neuroimaging to assess the extent of injury and to detect any associated intracranial and facial injury, intraorbital fragments, or hematoma. Orbital or cranial surgery may be necessary but may not affect the prognosis for the optic nerve. Therapy for indirect traumatic optic neuropathy is controversial. Although the prognosis for vision recovery has generally been regarded as poor, numerous reports describe spontaneous recovery of some visual function in a significant number of cases. The International Optic Nerve Trauma Study, a nonrandomized, multicenter, comparative analysis of treatment outcomes, found no clear benefit for treatment with intravenous corticosteroids or optic canal decompression, and no consensus exists for their use, whether alone or in combination.

One study of more than 10,000 head-injury patients compared treatment within the 8-hour window after trauma using high-dose corticosteroids versus placebo. The study was terminated early after initial analysis revealed that the corticosteroid group had a statistically significantly higher rate of mortality than the placebo group. This finding raises safety concerns for the use of high-dose corticosteroids in the treatment of traumatic optic neuropathy, particularly in patients with severe

head trauma.

Carta A, Ferrigno L, Salvo M, Bianchi-Marzoli S, Boschi A, Carta F. Visual prognosis after indirect traumatic optic neuropathy.

J Neurol Neurosurg Psychiatry. 2003;74(2):246–248.

Edwards P, Arango M, Balica L, et al; CRASH trial collaborators. Final results of MRC CRASH, a randomised placebocontrolled trial of intravenous corticosteroid in adults with head injury—outcomes at 6 months. Lancet. 2005;365(9475):1957– 1959.

Levin LA, Beck RW, Joseph MP, Seiff S, Kraker R. The treatment of traumatic optic neuropathy: the International Optic Nerve Trauma Study. Ophthalmology. 1999;106(7):1268–1277.

Steinsapir KD, Goldberg RA. Traumatic optic neuropathy: an evolving understanding. Am J Ophthalmol. 2011;151(6):928–933. Epub 2011 May 6.

Posterior ischemic optic neuropathy

Acute ischemic damage to the retrobulbar portion of the optic nerve is characterized by abrupt, often severe, vision loss, an RAPD, and initially normal-appearing optic discs. Posterior ischemic optic neuropathy (PION) is considered rare and is a diagnosis of exclusion. It occurs in 3 distinct scenarios: perioperative (most commonly in spine, cardiac, and head or neck procedures); arteritic, especially from giant cell arteritis; and nonarteritic (with risk factors and clinical course similar to those of NAION). Vision loss in perioperative PION is more commonly bilateral and profound. Perioperative PION has gained more widespread scrutiny because of the increasing number of reports and the potential medicolegal implications. Nearly all patients with perioperative PION have incurred substantial blood loss, hypotension, and prolonged anesthesia time. However, several case control studies do not show that any one factor clearly occurs more commonly in patients with PION than in patients who undergo similar surgeries but do not sustain perioperative vision loss. Additionally, reports have been published of patients with PION who lost less than 500 mL of blood and had systolic blood pressure >90 mm Hg. More than likely, the cause of vision loss is multifactorial and results from a combination of patient and perioperative factors. Patients with no history of previous surgery should undergo neuroimaging. Also, a careful evaluation for symptoms and laboratory evidence of GCA should be undertaken in older individuals. High-dose corticosteroid treatment is indicated for cases of proven GCA. Prognosis for vision recovery in PION is poor.

Berg KT, Harrison AR, Lee MS. Perioperative visual loss in ocular and nonocular surgery. Clin Ophthalmol. 2010;4:531–546. Lee LA, Roth S, Posner KL, et al. The American Society of Anesthesiologists Postoperative Visual Loss Registry: analysis of

93 spine surgery cases with postoperative visual loss. Anesthesiology. 2006;105(4):652–659.

Infiltrative optic neuropathy

Infiltration of the optic nerve by neoplastic or inflammatory cells results in progressive, often severe, vision loss. This visual dysfunction, which is often associated with pain, progresses over days to weeks, with or without other cranial nerve involvement. The optic neuropathy may present in 1 or both eyes and can herald systemic disease. With retrobulbar infiltration, the optic nerve head may appear normal initially. In cases of optic disc edema, the cellular infiltrate creates a swollen appearance that may be distinct from that of simple edema (see Fig 4-12). The presence of vitreous cells or peripheral vasculitis may raise concern for an infiltrative process. The most common causes of infiltration include leukemia, lymphoma, and granulomatous inflammation such as sarcoidosis, syphilis, tuberculosis, and fungal infections. Metastasis to the optic nerve is rare, usually occurring from breast or lung carcinoma. Carcinomatous infiltration of the meninges at the skull base may result in progressive involvement and dysfunction of multiple cranial nerves, including the optic nerves, which are affected in 15%–40% of cases. Onset may precede, coincide with, or follow diagnosis of