Optic Neuritis (ON)
Optic Neuritis (ON)
Optic neuritis (ON) is a rare autoimmune disease that attacks the central nervous system, causing loss of vision, eye pain, loss of color and visual field deficits.
What is Optic Neuritis (ON)?
This brain disease occurs when the body’s immune system accidentally attacks the central nervous system, specifically the optic nerves, and affects how sight is transmitted and understood by the brain. This condition can affect one (monocular) or both eyes (bilateral); children age 15 or younger typically experience bilateral ON.
In children, this autoimmune disease can cause an inflammation (swelling) that damages the myelin around the nerves (demyelination). Myelin acts as insulation (like a plastic covering on electrical wires), allowing the body’s electrical impulses that control normal functions to activate. When the myelin is damaged, it can slow down the body’s internal communication that manages movements and reactions, and in this case, vision.
ON can occur by itself or be part of multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM) or neuromyelitis optica (NMO). In 15% to 20% of the cases, ON is an initial symptom of MS and will occur in 50% of MS patients.
This rare condition impacts about 6 in 100,000 people, with higher incident rates in the northern U.S. and western Europe. ON affects approximately three times more women than men.
What are the signs and symptoms of Optic Neuritis (ON)?
Signs of ON can range in frequency and severity. Vision problems and eye pain improve two or three weeks after the first symptom in more than 90% of cases, whether or not treatment is provided. Alert your doctor if this specific improvement doesn’t occur or if other symptoms are present. Symptoms include:
- Afferent pupillary defect (a noticeable difference between the eyes during a light exam that tests dilation or the pupil’s opening and closing)
- Blindness in one or both eyes
- Blurry vision or loss of color (can be in one or both eyes)
- Eye pain and swelling (made worse with eye movement)
- Photopsias (flashes of light)
What are the causes of Optic Neuritis (ON)?
The exact cause of ON is unknown, but scientists believe there may be a combination of factors that trigger the autoimmune responses that cause damage. In some rare cases, ON develops from outside factors instead.
- Autoimmune, viral and bacterial diseases or infections – If your child has another autoimmune disease (like lupus or MS), there is an increased risk of developing ON. Other diseases including Epstein-Barr virus (mono), measles and Lyme disease have also been linked with NMO.
- Genetics – If someone in a family has ON, it is not guaranteed that other family members will inherit it, but there is an increased risk of developing it.
- Medication side effects – In this case, ON isn’t triggered by an autoimmune response; it’s caused by damage to the optic nerve from inadequate blood supply. This can be a side effect of certain medications, including antibiotics like tetracycline (broad spectrum, treating everything from acne to urinary tract infections and syphilis, linezolid (treating pneumonia or skin infections), amiodarone (treating heart conditions like arrhythmia and isoniazid (treating tuberculosis).