- 1.
What is optic neuritis?
Optic neuritis is any inflammation of the optic nerve. It may be idiopathic or associated with systemic disease.
- 2.
Which systemic diseases are associated with optic neuritis?
The most common disease associated with optic neuritis is multiple sclerosis (MS). However, neuromyelitis optica, syphilis, sarcoidosis, Lyme disease, and other collagen vascular diseases such as Wegener’s granulomatosis and systemic lupus erythematosus are less commonly associated.
- 3.
Who most commonly gets optic neuritis?
Women between the ages of 15 and 45 years are most commonly affected.
- 4.
What are the typical clinical findings in optic neuritis?
Optic neuritis causes acute or subacute visual loss that is preceded or accompanied by pain on eye movement and that may progress over 10 to 14 days. Visual acuity may range from 20/20 to no light perception. However, even if visual acuity is 20/20, the patient usually has a defect in color vision, contrast sensitivity, and visual field. If the neuritis is unilateral, an afferent pupillary defect is present. The optic disc may be normal or swollen.
- 5.
Which clinical test is most sensitive for patients with optic neuritis?
The most sensitive test—that is, the test most likely to be abnormal in a patient with optic neuritis—is contrast sensitivity.
- 6.
How common is pain on eye movement in patients with optic neuritis?
Pain around the eye or pain exacerbated with eye movement was present in 92% of patients in the Optic Neuritis Treatment Trial (ONTT).
- 7.
What visual field defects are found in patients with optic neuritis?
The classic visual field defect in optic neuritis is central scotoma. However, results of the ONTT showed that any optic nerve visual field defect is compatible with optic neuritis, including altitudinal defects and arcuate defects as well as diffuse visual field defects.
- 8.
What is the natural history of optic neuritis?
The visual loss of optic neuritis may progress over 10 to 14 days. At that point it should stabilize and shortly thereafter begin to improve.
- 9.
What is the expected visual outcome for patients with optic neuritis?
The ONTT found that at 12 months, 93% of patients were 20/40 or better, 69% were 20/20 or better, and 3% were 20/200 or worse. At 10 years, 91% of patients had acuity of 20/40 or better and 74% were 20/20. At 15 years, 66% had visual acuity of 20/20 or better in both eyes. On average, visual acuity was worse in those who developed MS.
- 10.
Are there any predictors of poor visual outcome?
The ONTT found that the only predictor for poor visual outcome was poor visual acuity at presentation. Nevertheless, all patients with an initial visual acuity of 20/200 or less showed some improvement. However, 5% of the patients were still 20/200 or less at 6 months.
- 11.
What were the objectives of the ONTT?
The ONTT was a multicenter, randomized, prospective clinical trial to determine whether corticosteroid treatment of optic neuritis was beneficial for visual outcome. A secondary objective was to determine the risk of developing MS in patients with optic neuritis. The patients who participated in the ONTT were randomized to three treatment arms. One group of patients received oral placebo; one group received oral prednisone, 1 mg/kg for 14 days; and one group received intravenous (IV) methylprednisolone (Solu-Medrol), 250 mg every 6 hours for 3 days, followed by oral prednisone, 1 mg/kg for 11 days.
- 12.
What were the conclusions of the ONTT regarding treatment of optic neuritis?
No treatment group had statistically significantly better visual acuity at 6 months. However, patients treated with IV methylprednisolone began to recover vision more quickly. The surprising result was that patients treated with oral prednisone, 1 mg/kg for 14 days, had an increased incidence (2×) of recurrence of optic neuritis in the affected or contralateral eye. The researchers concluded that oral prednisone at a dose of 1 mg/kg is contraindicated in the treatment of optic neuritis.
- 13.
What was the strongest predictor for the development of MS?
An abnormal magnetic resonance imaging (MRI) scan ( Fig. 31-1 ) was the strongest predictor for development of clinically definite MS at 2 years. Placebo-treated patients whose MRI scan at study entry showed two or more periventricular white matter lesions >3 mm had a 36% chance of developing MS within 2 years. Patients with one lesion had a 17% chance, and patients with no signal abnormalities had only a 3% chance.
