Synonyms: retrobulbar neuritis, papillitis
Optic neuritis (ON) is inflammation of the optic nerve. Classically there is a triad of clinical features - reduced vision, eye pain and impaired colour vision. Acute demyelinating ON is a common cause of ON in parts of the world where multiple sclerosis is common. However, there are many other possible causes which must not be overlooked, as they may require different and urgent management.
The term 'optic neuritis' means inflammatory optic neuropathy from any cause, but is sometimes used to refer to acute demyelinating optic neuritis. In this article, 'optic neuritis' (ON) refers to optic neuritis of any type, and 'acute demyelinating optic neuritis' (ADON) will be used for that specific form. Other terms used in the literature are papillitis (if the optic nerve head is affected) and retrobulbar neuritis (if the nerve is affected more posteriorly).
The first part of this article discusses ON of any type: its causes, assessment and diagnosis. The second part gives more detail about ADON in adults.
|Acute demyelinating ON||The most common cause of ON in regions where multiple sclerosis (MS) is relatively common (Caucasian populations and high latitudes).|
|Ischaemic optic neuropathies||Giant cell arteritis (cranial arteritis), anterior and posterior optic neuropathy, diabetic papillopathy.|
|Corticosteroid-responive ON||Sarcoidosis, systemic lupus erythematosus, Behçet's disease, neuromyelitis optica (Devic's syndrome - affects optic nerves and the spinal cord), autoimmune ON, chronic relapsing inflammatory ON.|
|Other inflammatory causes||Post-infection, post-vaccination, neuroretinitis, acute disseminated encephalomyelitis.|
|Infections||Tuberculosis, syphilis, Lyme disease, toxocariasis, helminthitis, viral ON (a rare complication of chickenpox), Q fever, periorbital infections (orbital cellulitis, severe suppurative sinusitis).|
|Nutritional||Vitamin B12 deficiency.|
|Drugs and toxins||Amiodarone, ethambutol, isoniazid, methanol intoxication, tobacco-methanol amblyopia.|
|Inherited||Leber's hereditary ON.|
|Optic neuritis in children||Following viral infection is a common cause.|
Presentation, assessment and diagnosis
The usual presentation is a triad of:
- Visual impairment
- Eye pain
- Dyschromatopsia (impairment of colour vision)
Other symptoms present in acute demyelinating optic neuritis (ADON) are:
- Light flashes (phosphenes or photopsias).
- Uhthoff's phenomenon - increased symptoms with raised body temperature (hot environment or exercise).
- Pulfrich's phenomenon - altered perception of the direction of movement, due to asymmetrical conduction in optic nerves.
- Fatigue - fading of vision.
- Full ophthalmological and neurological examination.
- In practice, it is important to assess whether the clinical picture is typical of ADON, or whether there are atypical features suggesting another cause (see table).
|Typical features of acute demyelinating optic neuritis||'Warning' or atypical features suggesting another cause|
|Adult patient age <45.
|Patient aged <12 or >50, black or Asian race.
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The diagnosis of acute demyelinating optic neuritis (ADON) is a clinical one. If the clinical picture is typical for ADON, initial assessment involves:
- Full ophthalmological examination.
- Testing of visual acuity, contrast and colour vision, visual field testing.
- MRI of the brain may be used to give information about the likelihood of developing multiple sclerosis (MS) (see below).
- Some studies suggest that testing of contrast vision, using specific charts, may yield similar information to MRI in this scenario.
- If there are atypical features, investigations depend on the clinical picture, and may include:
- Blood tests - eg full blood count, erythrocyte sedimentation rate, autoantibodies and syphilis serology.
- Serological testing for neuromyelitis optica immunoglobulin G (NMO-IgG).
- Chest X-ray - for suspected sarcoidosis, tuberculosis or malignancy.
- CT or MRI of brain and orbits.
- Lumbar puncture - for suspected central nervous system infection or inflammatory optic neuritis (cerebrospinal fluid is examined for immunoglobulins, oligoclonal bands and infection).
Acute demyelinating optic neuritis in adults
- Acute demyelinating optic neuritis (ADON) demographics closely follow those of multiple sclerosis (MS), which has a higher frequency in Caucasian populations and at higher latitudes. Children who migrate before puberty take on the MS incidence of the area to which they migrate.
- Annual incidence of ADON is approximately 5/100,000; prevalence is 115 per 100,000.
The pathology of ADON involves demyelination and axonal loss, probably due to an inflammatory process and a delayed hypersensitivity reaction. Recovery is due to remyelination and compensatory neuronal recruitment.
Presentation, diagnosis and investigations
These are explained above (see clinical features, and 'Presentation, assessment and diagnosis' and 'Investigations' sections).
- Refer to an ophthalmologist and/or neurologist. Usually, an ophthalmologist is involved in the initial assessment, diagnosis and treatment. Further management regarding the risk of MS (below) usually requires neurological expertise.
- Consider corticosteroids during the acute phase:
- Treatment with methylprednisolone speeds up visual recovery in the acute phase, but has no effect on final visual acuity. Side-effects of corticosteroids can be serious. Therefore, they are usually reserved for patients who need to hasten visual recovery, such as those with poor vision in the fellow eye or bilateral visual loss, or for occupational reasons.
- Recommended treatment is methylprednisolone 1 g daily for 3 days.
- Oral prednisolone is not recommended because of (uncertain) evidence that it may increase the recurrence rate.
- There is no treatment that can reverse poor visual outcome in the long-term.
- Information for patients is important (see prognosis section below).
- Consider brain MRI, to give information about the risk of developing MS.
- Consider referring to a neurologist for assessment of the patient's risk of developing MS, and the value of disease-modifying drugs in this context (see 'Role of disease modifying drugs', below).
- For the Pulfrich phenomenon (disturbed perception of movement, above), symptoms may be helped by using spectacles with a tinted lens over the unaffected eye, to balance the delay in conduction from the other side.
- For Uhthoff's phenomenon symptoms (worsening vision with raised body temperature), avoid hot environments and take cool drinks; reassure patients that this symptom is reversible and does not further damage vision.
- Intravenous immunoglobulin has generally been found to be of no benefit. One recent trial (small and non-randomised, using a different regimen) reported improved vision with immunoglobulin treatment.
- The prognosis for vision in ADON is usually good.
- The Optic Neuritis Treatment Trial (ONTT), was a large study of ADON with 15-year follow-up, and found that:
- 93% of patients showed improvement within 5 weeks of onset of ADON; vision continued to improve for up to 1 year. One year after onset, 93% had visual acuity better than 6/12 in the affected eye. At 15-year follow-up, 92% had acuity better than 6/12 in the affected eye, and only 1% had vision worse than 6/60 in both eyes.
- The severity of initial visual loss seems to be related to the final visual outcome; however, even with initial visual acuity of ≤6/60, 85% recover vision to 6/12 or better.
- Although visual outcome is good in objective tests, many patients experience subjective reductions in vision, colour vision, contrast sensitivity or depth/movement perception after recovery from ADON.
Risk of recurrence:
- ADON can recur in either eye.
- The risk of recurrence was 35% over 10 years in the ONTT.
Risk of developing MS:
- ADON is associated with MS.
- In the ONTT, for adults with a single episode of unilateral ADON, the risk of MS was 38% at 10 years after onset, and 50% at 15 years. Another study found the MS risk was 54% after 30 years. The risk of developing MS is lower for children and for men.
- MRI of the brain gives information about the risk of developing MS. The presence of white matter abnormalities increases the MS risk and their absence reduces it. In the ONTT, the risk of developing MS at 15-year follow-up was 25% for patients with no lesions on MRI, and 75% for those with white matter lesion(s).
Role of disease-modifying drugs:
- Interferon beta increases the time interval to relapse in MS. Trials suggest that, in a scenario such as a patient with ADON and white matter lesions on brain MRI, where the risk of developing MS is relatively high, interferon beta may similarly delay the onset of MS symptoms.
- However, bear in mind that:
- Many patients with a first episode of ADON and an abnormal MRI scan will not develop MS.
- Treatment is only partly effective, eg 6 years of interferon beta treatment prevents one relapse.
- The visual prognosis is good even if MS develops.
Discussion with patients:
- The association between ADON and MS causes anxiety for patients and can impact on insurance policies.
- It is important to emphasise that many ADON patients will not develop MS; even if they do, the prognosis regarding both vision and other disability can be good.
- Information about the prognosis can help patients to decide whether to undergo an MRI scan and whether to use beta interferon.
Further reading & references
- Hickman SJ et al. Optic Neuritis: An Update Typical and Atypical Optic Neuritis. Neuro-Ophthalmology 2008; 32: 237–248.
- Wilejto M, Shroff M, Buncic JR, et al; The clinical features, MRI findings, and outcome of optic neuritis in children. Neurology. 2006 Jul 25;67(2):258-62.
- Eva PR; Acute demyelinating optic neuropathy. Focus, Royal College of Ophthalmologists, issue 25, 2003
- Hickman SJ, Dalton CM, Miller DH, et al; Management of acute optic neuritis. Lancet. 2002 Dec 14;360(9349):1953-62.
- Shams PN, Plant GT; Optic neuritis: a review. Int MS J. 2009 Sep;16(3):82-9.
- Matiello M, Jacob A, Wingerchuk DM, et al; Neuromyelitis optica. Curr Opin Neurol. 2007 Jun;20(3):255-60.
- Tselis A, Perumal J, Caon C, et al; Treatment of corticosteroid refractory optic neuritis in multiple sclerosis Eur J Neurol. 2008 Nov;15(11):1163-7. Epub 2008 Aug 21.
- No authors listed; Visual function 15 years after optic neuritis: a final follow-up report from the Ophthalmology. 2008 Jun;115(6):1079-1082.e5. Epub 2007 Nov 5.
- No authors listed; Multiple sclerosis risk after optic neuritis: final optic neuritis treatment Arch Neurol. 2008 Jun;65(6):727-32.
|Original Author: Dr Olivia Scott||Current Version: Dr Naomi Hartree|
|Last Checked: 26/10/2010||Document ID: 1765 Version: 21||© EMIS|
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