Optic neuritis is the inflammation of the optic nerve. It may mainly involve the optic nerve head (papillitis), or only the posterior part of the nerve sparing the optic nerve head (retrobulbar neuritis).
Optic neuritis may be asymptomatic or may present with the following symptoms :
The diagnosis of acute demyelinating optic neuritis is based on the history, symptoms and clinical signs from the following eye tests:
In a patient having the first attack of acute demyelinating optic neuritis, in the presence of two or more white matter lesions on MRI (3mm diameter or larger, at least one lesion periventricular or ovoid), the recommended treatments is one of these :
In a patient with optic neuritis having fewer than two MRI white matter lesions, and in patients with established diagnosis of multiple sclerosis, and in patients with unilateral and severe visual loss or bilateral visual loss, treatment is intravenous methylprednisolone treatment followed by oral prednisone (as described above). This will hasten visual recovery but not influence the final visual outcome.
Intravenous methylprednisolone 1000 mg/day for 5 consecutive days followed by oral prednisone taper for optic neuritis with neuromyelitis optica.
Based on findings from the Optic Neuritis Treatment Trial, oral prednisone alone (without prior treatment with intravenous methylprednisolone) may increase the risk of recurrent optic neuritis and should be avoided.
Nonsteroidal anti-inflammatory agents may be prescribed for disabling ocular pain.
Treatment of the specific cancer in paraneoplastic optic neuropathy patients with chemotherapy and/or radiation therapy.
Even with no treatment, most patients of optic neuritis start to recover their lost vision within 2-3 weeks of the onset of symptoms, achieving the maximal improvement within 1-2 months or at the most within a year. Final visual outcome has been correlated with the initial severity of visual loss. In spite of visual recovery, patients continue to experience subtle visual problems which can be objectively documented as persistent defects in visual acuity, contrast sensitivity, color vision, visual field, visual-evoked potential and stereopsis.
In about 20% of patients, multiple sclerosis is associated with optic neruritis at the onset itself. Around 40% of affected individuals will develop multiple sclerosis at later stages. Recurrent episodes of optic neuritis in the initially affected or fellow eye may occur and the risk of recurrence is twofold greater in patients who are diagnosed with multiple sclerosis in the next ten years than in patients who do not develop multiple sclerosis .
These are the etiological factors associated with optic neuritis.
The annual incidence of optic neuritis is approximately 3–5 per 100,000 per year, while the prevalence is 115 per 100,000. The majority of patients who develop optic neuritis are between the ages of 20 and 50 years. Women are affected more commonly than men (2:1). In most cases, the pathogenesis of optic neuritis is inflammatory demyelination, whether or not multiple sclerosis is diagnosed clinically. Many cases where optic neuritis is the only presenting feature later are diagnosed with multiple sclerosis .
Optic neuritis is an inflammation of one or both optic nerves, often associated with multiple sclerosis and demyelinating diseases. Adults and women are more affected. It clinically presents with the triad of reduced vision, ocular or orbital pain and impaired colour vision. Nearly full visual recovery over time is common but residual visual defects may persist. Intravenous steroids are given in severe or bilateral cases to speed up recovery. Patients with an isolated incident of optic neuritis have better final visual outcome, whereas the prognosis is worse for patients with recurrent attacks or multiple sclerosis .
Cause: Optic neuritis is often associated with multiple sclerosis. It is believed that optic neuritis may have an autoimmune cause, where the body mistakenly destroys the nerve sheath (known as myelin) leading to nerve damage. Optic neuritis can also be associated with infections, neuromyelitis optica and autoimmune diseases.
Diagnosis: The eye doctor will take a detailed history of your symptoms and medical conditions that you and your close relatives have. A detailed examination of your eyes will be done, including an examination of the inside and back of the eyes with an instrument called ophthalmoscope. Magnetic resonance scans of the brain and eyes are often required. Blood tests may be required to rule out other diseases and infections.
Treatment and follow-up: Optic neuritis often improves spontaneously and a large number of people regain their vision almost completely in a year. The doctor may give you steroid medication through veins. Steroids reduce the inflammation in the optic nerve and speed up the visual recovery, but do not improve the extent of lost vision that you will recover. Steroids will also be given if multiple sclerosis is suspected. You may have repeat attacks of optic neuritis in future. Presence of multiple sclerosis or neuromyelitis optica leads to poor prognosis for long term visual recovery and preservation.