ESSENTIALS OF DIAGNOSIS
Subacute usually unilateral visual loss.
Pain exacerbated by eye movements.
Optic disk usually normal in acute stage but subsequently develops pallor.
Inflammatory optic neuropathy is strongly associated with demyelinating disease (typical optic neuritis), particularly multiple sclerosis but also acute disseminated encephalomyelitis. It also occurs in sarcoidosis; in neuromyelitis optica spectrum disorder, which is characterized by serum antibodies to aquaporin-4; in association with serum antibodies to myelin oligodendrocyte glycoprotein; following viral infection (usually in children); in varicella zoster virus infection; in autoimmune disorders, particularly systemic lupus erythematosus and Sjögren syndrome; during treatment with biologics; and by spread of inflammation from the meninges, orbital tissues, or paranasal sinuses.
Optic neuritis in demyelinating disease is characterized by unilateral loss of vision developing over a few days. Visual acuity ranges from 20/30 (6/9) to no perception of light, with more severe visual loss being associated with low serum vitamin D. In almost all cases there is pain behind the eye, exacerbated by eye movements. Field loss is usually central. There is particular loss of color vision and a relative afferent pupillary defect. In about two-thirds of cases, the optic nerve is normal during the acute stage (retrobulbar optic neuritis). In the remainder, the optic disk is swollen (papillitis) with occasional flame-shaped peripapillary hemorrhages. Visual acuity usually improves within 2–3 weeks and returns to 20/40 (6/12) or better in 95% of previously unaffected eyes. Optic atrophy subsequently develops if there has been damage to sufficient optic nerve fibers (eFigure 7–66). Any patient without a known diagnosis of multiple sclerosis with presumed demyelinating optic neuritis in which visual recovery does not occur or there are other atypical features, including continuing deterioration of vision or persisting pain after 2 weeks, should undergo further investigation; MRI of the head and orbits can look for periventricular white matter demyelination, examine for a lesion compressing the optic nerve, and identify atypical optic neuritis.
Bilateral optic atrophy with disk pallor due to optic neuritis.
In acute demyelinating optic neuritis, intravenous methylprednisolone (1 g daily for 3 days followed by a tapering course of oral prednisolone) has been shown to accelerate visual recovery but not to improve final vision. However, in clinical practice, the oral taper is not often prescribed, and oral methylprednisolone may be used. Use in an individual patient is determined by the degree of visual loss, the state of the fellow eye, and the patient’s visual requirements. Phenytoin may be neuroprotective in typical optic neuritis.
Atypical optic neuritis due to sarcoidosis, neuromyelitis optica, herpes zoster, or systemic lupus erythematosus generally has a poorer prognosis, requires immediate and more prolonged corticosteroid therapy, may require plasma exchange, and may necessitate long-term immunosuppression.