When something interferes with the optic nerve, it can affect your vision. It can happen if you have a tumor pressing on the nerve, or from things like glaucoma, lack of blood flow, and hereditary diseases.
The optic nerve is a bundle of fibers that relays electrical signals from the retina to the brain. It appears as a pinkish-yellow circle on your eye exam.
Dimming of Vision
The optic nerve relays visual information from your eye to your brain, helping you perceive images. When it is damaged or affected by disease, vision becomes blurry and dim. The onset of this symptom is often gradual, with the appearance of grey or dark patches in your vision over time. It can also occur suddenly, as a result of an injury or illness. If you experience this symptom, it is important to see your optometrist right away.
This symptom occurs when the optic nerve is damaged and unable to send the impulses required to process the light that hits your retina. The damage can be caused by a variety of conditions and diseases, including glaucoma, optic neuritis (swelling of the optic nerve), a stroke that affects the optic nerve, Leber hereditary optic neuropathy (LHON), and retinitis pigmentosa.
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Your doctor will diagnose the condition by performing an eye exam. They will take a detailed history to understand how your vision has changed and why. This may include a review of your family history and any medications you are taking. They will examine your eyes and look for the characteristic pale appearance of the optic nerve on the retinal disc. They will also assess your visual field, including looking for a wedge defect in the prechiasmal area or bitemporal hemianopsia in the postchiasmal area of the retina.
Typically, the optic nerve looks pale or waxy white on the fundus of the retina, and it is possible to distinguish between primary optic atrophy, in which the nerve fibers are dead due to cellular degeneration, and secondary optic atrophy, in which the peripheral nerve has become overgrown with glial cells. The doctor can also use electrophysiology or optical coherence tomography to assess the thickness of the nerve fiber layer and determine if there is a change in the normal pattern.
Reduced Field of Vision
The optic nerve is a bundle of over 1.2 million axons of retinal ganglion cells that carries visual information from the eye to the brain. It is myelinated by oligodendrocytes which do not regenerate after injury and in optic atrophy the myelination is shrunken. This leads to a reduction of the size of the optic nerve head and the appearance of a pale disc (pallor). The condition is usually a late stage in a process that damages the optic nerve and it cannot be reversed.
Almost anything that affects the function of the ganglion cells in this area can cause optic atrophy. This includes conditions in the eye itself such as glaucoma, loss of blood flow due to a tumor, trauma or other causes, as well as damage along the pathway from the eyes to the brain (optic neuritis, papilledema, etc) and congenital diseases like Leber’s hereditary optic atrophy or Autosomal Dominant Optic Atrophy Type 1.
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It is important to have any changes in vision examined by an ophthalmologist. They will use an instrument called an ophthalmoscope to look in your eye and will check your field of vision, color vision, side vision and pupil reaction. They will also examine the back of your eye (the optic nerve head) and may notice a paleness to it that indicates a loss of nerve fibers. Treatment to prevent further vision loss and treat any underlying chronic health problems will help slow the progression of optic atrophy. However, once the nerve fibers are lost they can not be regained. It is therefore important to see a healthcare provider as soon as you start to experience any vision changes.
Blurred Vision
A loss of sharpness of vision due to optic atrophy is often described as blurred vision. This is due to damage to the cells of your optic nerve, which carry images from your eyes to your brain. This can happen from many conditions, including long-term lack of blood flow to the optic nerve (ischemic optic neuropathy), certain drugs, glaucoma and other diseases. This condition can cause irreversible damage to your vision, but it can be treated if you see an eye doctor as soon as possible.
Your provider will ask you questions about your symptoms and do a physical exam. They may use a special tool called an indirect ophthalmoscope to check your vision. The optic disc will look pale, indicating the change in blood flow to it. The retina and other structures of your eye will also be examined, often after dilating your pupils with drops that contain a sympathomimetic or cycloplegic (eg, 2.5% phenylephrine or 1% cyclopentolate).
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Sudden blurred vision can be a warning sign for some neurological problems such as stroke or hemorrhage, or it can indicate that you have suffered a transient ischemic attack, or TIA. This type of stroke is often referred to as “mini-stroke” because the symptoms resolve quickly, but it should be treated just as seriously as a full stroke.
You may have a headache and blurred vision, especially when you are reading or doing other visually demanding activities. This can be a symptom of migraine headaches, which can also include other symptoms such as sensitivity to light, numbness or weakness in your arms and legs, and nausea. You should get treatment for your migraine headaches as soon as you can to prevent worsening of the symptoms and other health issues.
Spots in the Vision
Symptoms of optic atrophy can be caused by any condition that damages the optic nerve or causes it to degrade. It can occur in one or both eyes. The first step in diagnosing the problem is getting a complete medical history including all medications, supplements and vitamins you take. Some common causes of optic atrophy include herpes simplex virus infections, certain antibiotics and anti-cancer drugs, exposure to toxins like tobacco and methanol (wood alcohol) or lack of blood flow to the optic nerve which can cause it to die. Vitamin deficiencies can also be the culprit.
A doctor can diagnose the problem by doing a dilated eye exam. During this test, the doctor can see the back of the eye and look for early changes in the optic nerve. They can also do a visual field test and measure color and contrast vision. They can also check your pupil reaction to light and look for shaking of the head (nystagmus) or eye crossing or focusing problems (diplopia).
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Treatment of optic atrophy is aimed at addressing the underlying cause. For example, removing excess fluid pressure around the brain and spinal cord (hydrocephalus) can help prevent further damage to the optic nerve in patients with that condition.
Optical atrophy can usually be prevented by regular visits to an eye care specialist and taking standard safety precautions. Everyone should have a routine dilated eye exam and tell the doctor right away if they notice any new problems with their vision. It is especially important for older adults to get regular health exams and manage their blood pressure. Preventative measures such as using protective eyewear while working and keeping to a healthy diet can also decrease the risk of optic atrophy.
