Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Optic neuritis is inflammation of the optic nerve, the structure that
connects the eye to the brain. The optic nerve consists of nerve tracts (axons)
that originate in the retina of each eye. The optic nerve carries visual
information from the retina to the nerve cells in the brain stem, where the
information is relayed to the area of the brain that recognizes vision (the
occipital cortex).
Optic neuritis can occur in children or adults and may involve either one or
both optic nerves. Optic neuritis typically affects young adults ranging from
18-45 years of age, with a mean age of 30-35 years. There is a strong female
predominance. The annual incidence is approximately 5/100,000, with a total
prevalence estimated to be 115/100,000.
What causes optic neuritis?
The precise cause of optic neuritis is unknown, but it is thought to be a
type of autoimmune disorder. The immune system is generally used to fight
infection by creating a reaction that combats bacteria, viruses, fungi, and
other foreign proteins. In autoimmune diseases, this reaction is mistakenly
directed against a normal part of the body, creating inflammation and potential
damage. In the case of optic neuritis, the optic nerve becomes swollen and its
function is impaired. Inflammation of the optic nerve causes loss of vision
because of the swelling and destruction of the protective myelin sheath that
covers and insulates the optic nerve. Direct damage to the nerve tracts (axons)
may also play a role in nerve destruction.
Optic neuritis most commonly develops due to an autoimmune disorder that may
be triggered by a viral infection. In some people, signs and symptoms of optic
neuritis may be an indication of multiple sclerosis, a disease in which the
immune system attacks the myelin sheath covering nerve fibers in the brain and
spinal cord, resulting in inflammation and damage to nerve cells in the brain
and spinal cord. Demyelinating optic neuritis is another term for this eye
condition. In optic neuritis resulting from demyelinating disease, particularly
multiple sclerosis, there may be recurrences of optic neuritis over time.
In 15%-20% of people who eventually develop multiple sclerosis,
optic neuritis is their first symptom. The risk of developing multiple sclerosis
following one episode of optic neuritis is approximately 50% within 15
years of the episode of optic neuritis. On MRI scanning, almost half of the
patients with optic neuritis (and no history or clinical evidence of multiple
sclerosis) have abnormal brain white matter changes consistent with multiple
sclerosis. In patients undergoing MRI scans of the brain at the time of the
initial attack of optic neuritis, the finding of brain lesions on MRI images
increased the risk of development of later multiple sclerosis threefold versus
people with normal MRI scans. However, almost half of patients with any brain
lesions on MRI at the time of the initial episode of optic neuritis will not
have developed multiple sclerosis 10 years later.
Another autoimmune condition that causes optic neuritis is neuromyelitis
optica. In this unusual condition, inflammation occurs in the optic nerve and
spinal cord but usually not within the brain as often as in multiple sclerosis.
Optic neuritis arising from neuromyelitis optica is more severe than optic
neuritis associated with multiple sclerosis.
There are many causes of optic neuritis unassociated with multiple sclerosis,
including:
Cranial arteritis:
This is an inflammation of the lining of the arteries within the skull. Inflamed
cranial arteries can block blood flow to your eyes and brain, which may cause
permanent vision loss or a stroke. Cranial arteritis is most likely to occur in
adults 60-90 years of age. This condition is also known as temporal arteritis or
giant cell arteritis (GCA).
Diabetes: Diabetes is a condition in which the
body cannot make or properly use insulin, a hormone that regulates the amount of
sugar in the blood and other tissues. People with diabetes are at an increased
risk of developing disorders of the optic nerve, including optic neuritis, most
likely from decreased blood flow to the optic nerve.
Autoimmune diseases (such as systemic lupus) may cause
inflammation of blood vessels (vasculitis) nourishing the optic nerve.
Drugs.
Some drugs have been associated with the development of optic neuritis. These
include ethambutol (Myambutol) and certain antibiotics.
Toxins: Lead, methyl alcohol,
quinine, and arsenic may cause vision loss and other symptoms that may mimic
optic neuritis.
Radiation therapy to the head is an uncommon cause of optic
neuritis.
Leber's hereditary optic neuropathy, an inherited form of vision
loss that affects mostly males in their 20s or 30s, may cause optic neuritis.
However, the basic cause of optic neuritis is often unknown.
The term "optic neuropathy" is a more general term used to describe any
condition that results in damage to the optic nerve. Optic neuritis is a
specific type of optic neuropathy resulting from inflammation. Common
noninflammatory causes of optic neuropathy include glaucoma, blocked or limited
blood flow, direct trauma to the optic nerve(s), many neurological diseases,
elevated intracranial pressure, primary and metastatic optic nerve tumors,
nutritional deficiencies, and toxic exposure, including alcohol and tobacco,
intraocular inflammation, and injuries. Trauma can interfere with the nerve's
ability to conduct electrical impulses. All of these may cause vision loss and
other symptoms that may mimic optic neuritis.
Sinus infection (sinusitis) signs and symptoms include headache, fever, and facial tenderness, pressure, or pain. Treatments of sinus infections are generally with antibiotics and at times, home remedies.
Diabetes mellitus is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are referred to as type 1 (insulin dependent) and type 2 (non-insulin dependent). Symptoms of diabetes include increased urine output, thirst, hunger, and fatigue. Treatment of diabetes depends on the type.
HIV (human immunodeficiency virus) is the cause of AIDS (acquired immunodeficiency syndrome). HIV is a type of virus called a retrovirus, which infects humans when it comes in contact with a break in the skin or tissues such as those that line the vagina, anal area, mouth, or eyes.
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis bacteria. Symptoms include weakness, fever, weight loss, night sweats and in worse cases, chest pain, shortness of breath, and coughing up blood. A person with an active infection (a positive TB skin test, abnormal chest x-ray and TB bacteria in their sputum) requires treatment with izoniazid, rifampin, ethambutol and pyrazinaide.
A stroke results from impaired oxygen delivery to brain cells via the bloodstream. A stroke is also referred to as a CVA, or cerebrovascular incident. Symptoms of stroke include: sudden numbness or weakness of the face, arm or leg. Sudden confusion, trouble speaking or understanding. Sudden trouble seeing in one or both eyes, sudden trouble walking, dizziness, or loss of balance, and/or sudden severe headache with no known cause. A TIA, or transient ischemic attack is a short-lived temporary impairment of the brain caused by loss of blood supply. Stroke is a medical emergency.
Lyme disease is a bacterial illness, which is spread by ticks when they bite the skin. Initially the disease affects the skin causing a reddish rash associated with flu-like symptoms. It takes weeks to months after the initial redness of the skin for its effects to spread throughout the body. Lyme disease can be treated with antibiotics. Lyme disease can be prevented by using tick avoidance techniques.
Systemic lupus erythematosus is a condition characterized by chronic inflammation of body tissues caused by autoimmune disease. Lupus can cause disease of the skin, heart, lungs, kidneys, joints, and nervous
system. When only the skin is involved, the condition is called discoid lupus.
When internal organs are involved, the condition is called systemic lupus
erythematosus (SLE).
Multiple sclerosis (MS) is a disease which progressively injures the nerves of the brain and spinal cord, reflected by alterations of virtually every sensory or motor function in the body. The cause of MS is primarily unknown. There are different types of MS including relapsing-remitting MS, primary-progressive MS, and secondary-progressive MS. Symptoms of MS rang from mild to severe and examples include visual disturbances, muscle weakness, spasm, and fatigue. Decreased concentration, memory loss, and impaired judgment. Treatment for MS is generally with medications.
Sarcoidosis, a disease resulting from chronic inflammation, causes small lumps (granulomas) to develop in a great range of body tissues and can appear in almost any body organ. However, sarcoidosis most often starts in the lungs or lymph nodes.
Glaucoma is a common eye condition in which the fluid pressure inside the eye rises because of slowed fluid drainage from the eye. If untreated, glaucoma may damage the optic nerve and other parts of the eye, causing the loss of vision or even blindness.
The hepatitis B virus is a unique, coated DNA virus belonging to the Hepadnaviridae family of viruses. The course of the virus is determined primarily by the age at which the infection is acquired and the interaction between the virus and the body's immune system. Successful treatment is associated with a reduction in liver injury and fibrosis (scarring), a decreased likelihood of developing cirrhosis and its complications, including liver cancer, and a prolonged survival.
Toxoplasmosis (toxo) is a parasitic infection that causes flulike symptoms, swollen lymph nodes, and muscle aches and pains that may last from a few days to several weeks. Toxoplasmosis can be contracted by touching the hands to the mouth after gardening, cleaning a cat's litter box, or anything that came into contact with cat feces. Toxoplasmosis can also be contracted by eating raw or partly cooked meat, especially pork or lamb, or touching the hands to the mouth after contact with raw or undercooked meat.
Encephalitis is a brain inflammation that causes sudden fever, vomiting, headache, light sensitivity, stiff neck and back, drowsiness, and irritability. Meningitis is an infection that causes inflammation of the meninges that surround the brain and spinal cord. Symptoms of meningitis include high fever, headache, nausea, vomiting, and stiff neck.
Syphilis, a sexually transmitted disease, is caused by a microscopic, wormlike bacterial organism called a spirochete. There are three stages of syphilis. The first involves the formation of the chancre. The second stage often includes hair loss, a sore throat, white patches in the nose, mouth, and vagina, fever, headaches, and a skin rash. The third stage can cause extensive damage to the internal organs and the brain, and can lead to death. Though early infection often resolves on its own, treatment usually varies based on the stage of the infection at the time of diagnosis.
Bees, wasps, and fire ants are related insects that belong to the Hymenoptera order. There are thousands of species of wasps found throughout the world. Common wasps are yellow jackets and hornets. Types of bees include honey bees, the Africanized honey bee (killer bee), and the bumble bee. There are four types of reactions to a bee or wasp sting; 1) local reaction, 2) systemic allergic reaction, 3) toxic reaction, and 4) delayed reaction. Individuals who have a systemic or toxic reaction generally require immediate medical treatment to prevent anaphylactic reaction, and possibly death.
Cat scratch disease (CSD or cat scratch fever), a bacterial disease caused by Bartonella henselae, is characterized by fever, headache, fatigue, poor appetite, swelling of the lymph nodes, and mild infection at the site of the bite or scratch. Cats that carry B. henselae don't show signs of illness. Approximately 40% of cats carry the bacteria at some point in their lives.
Neuromyelitis optica (Devic's syndrome) is a disease of the CNS that affects the optic nerves and spinal cord. People with neuromyelitis optica develop optic neuritis and transverse myelitis. There is no cure for neuromyelitis optica; however, there are therapies to treat attacks when they occur.
Parry-Romberg syndrome is a rare disorder that is characterized by a slow progressive atrophy of the skin and soft tissues of half of the face. The facial changes generally begin between the ages of 5 and 15 years. There is no treatment or cure for Parry-Romberg syndrome.
Cat scratch disease (CSD) is a bacterial disease caused by Bartonella
henselae. Most people with CSD have been bitten or scratched by a cat and
developed a mild infection at the point of injury. Lymph nodes, especially those
around the head, neck, and upper limbs, become swollen. Additionally, a person
with CSD may experience fever, headache, fatigue, and a poor appetite. Rare
complications of B. henselae infection are bacillary angiomatosis and Parinaud's
oculolandular syndrome.
Can my cat transmit Bartonella henselae to me?
Sometimes, yes, cats can spread B. henselae to people. Most people get CSD
from cat bites and scratches. Kittens are more likely to be infected and to pass
the bacterium to people. About 40% of cats carry B. henselae at some time in
their lives. Cats that carry B. henselae do not show any signs of illness;
therefore, you cannot tell w...
Eyesight RSS
Healthy Living Tips
This site complies with the