Description
Optic neuritis (ON) produces acute, and usually self-limiting, visual impairment.
- Retrobulbar neuritis is an ON where the optic disc appears normal during the acute episode. It accounts for the majority of cases and is most often associated with Multiple Sclerosis (MS, see previous condition).
- Papillitis is an optic neuritis with disc swelling. It is more common in children, and in association with infections.
- Neuroretinitis is a papillitis with retinal ganglion cell layer involvement and is the least common type of optic neuritis. It is associated with intraocular infection or inflammation, e.g. Bartonella henselae, known as Cat Scratch Disease.
Possible causes of ON, other than MS, are many and varied. These include recent viral infections; adjacent infections of the orbit, paranasal sinuses or meninges; or other intraocular inflammation in associated conditions including Syphilis, Lyme Disease, Sarcoidosis, Toxoplasmosis, Bechet disease; Childhood viral infections – Chicken pox (varicella zoster virus), Measles, Mumps. Often no cause may be found.
Symptoms
The classic triad of optic neuritis consists of (1) loss of vision, (2) eye pain, and (3) impaired color vision. Deterioration in vision with a time-course of more than a few days, the absence of pain, or the presence of other neurological symptoms, may prompt consideration of an alternative diagnosis.
Signs
Acuity is variable. Color vision and contrast sensitivity are usually impaired. Visual field defects are common, and a relative afferent pupillary defect is usual in unilateral cases. In retrobulbar neuritis, the disc appears quite normal, whereas in papillitis, the optic disc is swollen and hyperemic, with or without peripapillary flame-shaped hemorrhages. A bilateral papillitis is the most common presentation in childhood viral infections. Neuroretinitis is a papillitis with a macular star composed of hard exudates. A full neurological examination should be performed on all patients.
Prevalence
Rare (approximately 1 per 20,000 per year).
Significance
It is important to identify and treat the underlying cause of ON.
Differential Diagnosis
Arteritic Ischemic Optic Neuropathy, Nonarteritic Ischemic Optic Neuropathy, Papilledema, Hypertensive Retinopathy, Diabetic Papillopathy, Leber Hereditary Optic Neuropathy, Toxic Optic Neuropathy.
See Also
See list of some possible causative conditions above, in Description.
Management
Investigations
If the patient has not previously been assessed for MS, or it is a first episode of ON, then Magnetic resonance imaging (MRI) and other evaluations for MS may be indicated. Other investigations may include:
- Visual evoked potentials – increased latency and decreased amplitude are characteristic of ON.
- Additional blood tests – to identify the etiology.
Oral and IV Medications
The most important aspect of inflammatory ON management is rapid diagnosis and identification of the underlying cause, in order to allow the best possible improvement of visual function. Systemic infections may require appropriate antibiotic treatment. Severe or bilateral optic neuritis may warrant consideration of intravenous steroids, although no long-term benefit may result.
Review
Review is conducted at 1 to 3 month intervals, and repeat MRI is often performed after 1 year. When ON is secondary to causes other than MS, the majority of patients recover good to excellent vision. However, reduced colour and contrast sensitivity are often permanent; and optic atrophy may develop, especially with recurrent attacks.
Figure 1.
Optic papillitis showing hyperemic disc swelling, peripapillary hemorrhages and distension of axons. No cause was found.
Figure 2.
Neuroretinitis due to cat scratch disease in a 13year old patient, showing papillitis and macular star exudates in the nerve fibre layer.
