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  • Current Management of Optic Neuritis

    Neuro-Ophthalmology/Orbit
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    New research by the Optic Neuritis Study Group has found that if magnetic resonance imaging (MRI) shows the presence of 1 or more white matter abnormalities (plaques) in patients with optic neuritis (ON), it is much more likely that those patients will develop multiple sclerosis (MS) in the next 10 years than ON patients with normal MRIs. This understanding of the relationship between ON and MS has led to new patient management paradigms that offer more effective treatment to prevent or delay development of this condition. Ophthalmologists aiming to provide the most current and optimal patient care must be aware of the nuances of diagnosing and treating ON, the onset of which often signals the development of MS. Luckily, the evaluation and treatment of ON patients are relatively straightforward, and the guidelines provided herein should serve as a framework for the management of these patients.

    Presentation

    A healthy 18-to-46-year-old man/woman presents with unilateral visual loss of 1 day’s duration. An ipsilateral relative afferent pupillary defect is present. The optic nerve head is either mildly swollen or normal. The eye examination is otherwise normal. This patient almost certainly has ON, which is the most common optic neuropathy encountered in patients in the 18-50 year age range. Misconceptions and red flags regarding presentation include:

    • Peripheral visual deficit. ON does not necessarily affect visual acuity, so virtually any visual field defect can occur in patients with this condition.
    • A lack of pain or discomfort should give one pause, but it does not rule out ON; 92% of patients with ON have some discomfort.
    • The presence of more than mild optic disc swelling and/or the presence of macular edema or exudate (Figure 1) should prompt evaluation for other causes of optic nerve inflammation (e.g., sarcoidosis or cat scratch disease).
     
    Courtesy Karl Golnik, MD.
    Figure 1. Disc Swelling in Optic Neuritis.

    Evaluation

    MRI, fluid attenuation inversion recovery (FLAIR) sequences, and gadolinium administration usually demonstrate optic nerve enhancement. More importantly, prognosis for the development of MS can be assessed. Other ancillary testing (e.g., blood tests, chest radiographs, etc.) are unnecessary in otherwise healthy young adults.

    Treatment

    The physician should treat ON by either observation or administration of intravenous (IV) corticosteroids (1 gm methylprednisolone/day x 3 days) followed by an oral corticosteroid taper (1 mg/kg/day x 11 days). Treatment with corticosteroids has been shown to: (1) relieve pain; (2) increase the rate of visual recovery (not the final visual recovery); and (3) decrease the risk of developing MS over the following 2 years, if the initial MRI shows 2 or more plaques. Intravenous corticosteroids can be given as outpatient therapy at an infusion center or at home through a home health care agency.

    Treatment with oral corticosteroids alone in moderate doses (1 mg/kg/day) results in more frequent and subsequent attacks of ON and is, therefore, contraindicated for treatment. Treatment, therefore, depends, in part on the MRI: If the MRI is normal, the patient may decide whether observation or corticosteroids are appropriate based on the degree of pain and the desire for more rapid visual recovery. If the MRI shows 2 or more plaques, corticosteroids (IV and oral taper) can be strongly recommended to reduce the chance of developing MS over the next 2 years.

    Prognosis for Visual Recovery

    The prognosis for visual recovery is excellent; 93% of patients recover vision of at least 20/40 over several months. Furthermore, 10 years after the initial ON, 92% of patients have a visual acuity of 20/40 or better (Am J Ophthalmol. 2004;137:77-83). At least 1 more attack of ON occurred in 35% of patients during the 10 years after initial presentation.

    Prognosis for Development of MS

    MS develops in 38% of patients over the 10 years following an episode of ON (Arch Ophthalmol. 2003;121:944-949). However, if the MRI is normal, only 22% of patients develop MS, and in this group, no patients with painless loss of vision, no light perception, or severe optic disc swelling will develop MS either. If 1 or more plaques are present, 56% of patients will develop MS over the 10-year span. The risk of developing MS can be decreased by treating high-risk ON patients, who can be identified by the presence of plaques on MRI, with immunomodulating agents such as interferon beta-1a (Lancet. 2004;364:1463-1464). Thus, high risk patients should be referred for systemic neurologic evaluation and possible treatment.

    Follow-up

    Regardless of treatment, reevaluation of patients with ON should occur about 4 to 6 weeks after presentation to ensure that the clinical course goes as expected with a gradual improvement in visual function. Also, by establishing a baseline status (e.g., acuity, color vision, and automated perimetry) at 3 to 6 months, the treating physician can more accurately detect any change in visual function, if the patient should return with new symptoms at a later date.

    References
    1. Optic Neuritis Study Group. Visual function more than 10 years after optic neuritis: experience of the optic neuritis treatment trial. Am J Ophthalmol. 2004;137:77-83.
    2. Optic Neuritis Study Group. High- and low-risk profiles for the development of multiple sclerosis within 10 years after optic neuritis. Arch Ophthalmol. 2003;121:944-949.
    3. Filippi M, Rovaris M, Inglese M, et al. Interferon beta-1a for brain tissue loss in patients at presentation with syndromes suggestive of multiple sclerosis: a randomised, double-blind, placebo-controlled trial. Lancet. 2004;364:1463-1464.

    Author Disclosure

    The author states that he has no financial relationship with the manufacturer or provider of any product or service discussed in this article or with the manufacturer or provider of any competing product or service.