Optic Atrophy

What is Optic Atrophy?

Optic atrophy refers to a condition where the optic nerve, which connects our eye to the brain, shrinks due to the breakdown of specific nerve cells (or retinal ganglion cell (RGC) axons). Most people use the term “optic atrophy”, but a more accurate name would be “optic neuropathy”. There is some disagreement about this term, though, because in certain situations, like initial optic atrophy or brain injuries, optic neuropathy might not be present.

Optic atrophy is essentially the final stage of a disease that affects the part of our vision pathway that connects the retina (the part of our eye that senses light) to the brain. One key sign of this condition is the pale appearance (or pallor) of the optic disc, a circular area at the back of the eye where the optic nerve enters. While the peripheral nervous system (the nerves outside the brain and spinal cord) can typically repair and regenerate itself, the central nervous system (our brain and spinal cord) is generally unable to do so. In the case of the optic nerve, it consists of large numbers of axons (nerve fibers) that are insulated by certain brain cells which prevent regrowth.

The optic nerve behaves more like a set of nerve connections in the brain rather than a typical peripheral nerve due to its structure and makeup. Damage to small blood vessels supplying the optic nerve head causes the pale appearance of the optic disc seen in optic atrophy. This nerve and blood vessel breakdown lays the foundation for the development of optic atrophy.

When light is shined onto the back of the eye, the light bounces back through the nerve fibers. This light, when it reflects off the small blood vessels on the optic disc, results in the typical yellow-pink color of a healthy optic disc. This appearance can be altered in individuals with eye disorders like cataracts or in those who have had lens replacement surgery.

After damage to the optic nerve, it generally takes about a month to six weeks to see the onset of optic disc pallor. In more severe cases, the optic disc becomes a chalky white color. This whitening contrasts with the surrounding red-colored retina (the part of our eye that senses light). The specific processes causing the optic disc pallor in optic atrophy are not entirely understood. It is assumed that the loss of nerve fibers and rearrangement of specific brain cells contribute to disc pallor. When the nerve shrinks due to various factors, this can lead to the loss of smaller blood vessels and potential scarring, contributing to the pale appearance of the optic disc seen in this condition.

Identifying optic atrophy can be crucial for patient’s health. Therefore, it is essential to understand this relatively common condition. This explanation provides a basic understanding of optic atrophy.

What Causes Optic Atrophy?

Optic atrophy, a condition that affects the optic nerve in the eye, can be caused by many different things. Some people find it useful to remember these causes using the acronym VIN DITTCH MD, which stands for: Vascular (related to blood vessels), Inflammatory and infectious, Neoplastic or compressive (meaning related to tumors or pressure), primary Demyelinating disease or idiopathic optic neuritis (conditions affecting the coating of the nerve cells), Toxic, Traumatic, Congenital (conditions present from birth), Hereditary (passed down from family members), Metabolic and endocrine causes (relating to our body’s chemical processes and hormones), and Degenerative (conditions that get worse over time).

In a study conducted in Malaysia, the main causes of optic atrophy that wasn’t related to glaucoma were found to be tumors in the head and brain, inherited conditions present from birth, hydrocephalus (a condition where there’s too much fluid in the brain), trauma (injury), and vascular causes (related to blood vessels).

There are a number of specific situations in which optic atrophy can occur, including:

Congenital (present from birth) diseases affecting the optic nerves: certain types of optic atrophy that can be inherited, and ones that associate with wider health conditions or neurological (nervous system) conditions.

Tumors or pressure put on the optic nerve due to conditions such as pituitary adenomas, intracranial meningiomas, aneurysms, and mucoceles.

Conditions that affect the blood vessels. Some of these include arteritic and nonarteritic anterior ischemic optic neuropathy (AION and NAION), which is where the blood supply to the optic nerve is blocked, as well as conditions like central retinal artery occlusion and carotid artery occlusion.

Inflammatory diseases like demyelinating optic neuritis, which include conditions like multiple sclerosis, Devic’s disease, and others such as sarcoidosis, systemic lupus erythematosus.

Infections, such as syphilis, tuberculosis, Lyme disease, Aspergillosis, Cryptococcus, chickenpox, measles, and mumps.

Nutritional deficiencies and exposure to toxins, which can cause conditions like nutritional amblyopia and thyroid ophthalmopathy, among others.

Trauma to the optic nerve caused by injuries, damage due to orbital fracture or foreign bodies.

Swelling of the optic nerve resulting due to conditions such as retinitis pigmentosa and macular dystrophies.

By understanding the causes, proper steps can be taken to diagnose and treat optic atrophy.

Risk Factors and Frequency for Optic Atrophy

Optic atrophy, a condition that can cause blindness, has varying levels of prevalence around the world. It’s been identified as one of the main reasons for blindness in countries like Israel, Japan, Scotland, and Zaire. Some studies even found it to directly cause a certain percentage of all blindness cases.

• In a study in Oman, 5% of blindness cases were due to optic atrophy.
• A study in Egypt found that in areas with more people, 4.1% of blindness was due to optic atrophy, while in less populated areas, the percentage was 1.2%.
• In southern Germany, a study of people who were newly registered as blind found that per 100,000 people per year, about 2.86 people became blind due to optic atrophy.
• In the Baltimore area of the United States, no white people were found to be blind due to optic atrophy. However, 1.9% of African-Americans were, leading to an overall prevalence of 0.8%.
• In another US study, 0.83% of people were found to be blind in both eyes. Out of these people, three had optic atrophy.

Signs and Symptoms of Optic Atrophy

Optic atrophy is a condition where the optic nerve, which transmits visual information from the eye to the brain, becomes damaged. Patients often notice blurred vision or a complete loss of vision. There are many potential causes for optic atrophy, and when a doctor is diagnosing the condition, they’ll need to understand the patient’s full medical history. This might include information about underlying health conditions, such as diabetes or thyroid disorders, medication use, lifestyle factors like smoking or drug use, and any past surgeries or illnesses.

Symptoms of optic atrophy can include sudden and severe vision loss, associated with eye pain when moving the eye. A common cause of optic atrophy is optic neuritis, which affects people between the ages of 10 and 50. Another possible cause is Anterior Ischemic Optic Neuropathy (AION), which usually affects people over the age of 50 and is associated with headaches and tenderness in the temples. In other cases, particularly with tumors, the visual impairment might steadily worsen over time. Look out for a gradual decrease in color saturation or contrast sensitivity, with red color loss often indicating optic neuritis, and early struggles to identify blue-yellow color as a marker of dominant optic atrophy.

When a healthcare professional examines a patient’s eye, they might notice a decrease in visual acuity, contrast sensitivity, and potential abnormal pupil response. The optic disc appears differently on an ophthalmoscope depending on the optic atrophy degree. Advanced cases display a chalky white disc, while earlier stages might have more subtle changes. One common early sign is the loss of peripapillary retinal striations, which are dark bands resembling rake marks seen on the soil.

There are multiple types of optic atrophy:

• Primary optic atrophy: Occurs without any preceding optic nerve swelling and can be caused by various conditions like trauma, inflammation, or heredity.
• Secondary optic atrophy: Comes after optic disc swelling caused by conditions like papilledema, optic neuritis, or AION.
• Consecutive optic atrophy: Associated with diseases affecting the inner retina or its blood supply like retinitis pigmentosa, retinochoroiditis, among others.
• Glaucomatous optic atrophy: Characterized by specific changes in the optic disc brought on by an increase in certain fluids in your eye; this type won’t be further considered in this article.
• Ascending and Descending optic atrophy: Can result from injury to the retinal elements or optic nerve leading to degeneration and loss of vision.
• Partial optic atrophy: Only part of the optic nerve is damaged, and visual impairment can vary significantly. In cases where only the papillomacular fibers atrophy, the optic disc may pale only on the temporal side.
• Total optic atrophy: Presents complete loss of nerve fibers, leading to a completely pale optic disc with no light perception.

Understanding and identifying these various types of optic atrophy can help healthcare professionals to design the most effective treatment plan for patients.

Testing for Optic Atrophy

For conditions affecting the optic nerve, like optic atrophy, various tests can be conducted based on the suspected cause of the condition.

Visual field tests help to identify changes in your field of vision, which is useful for diagnosing and monitoring your eye health. The 30-2 program is the most effective for optic atrophy and can detect blind spots, areas of partial vision loss (scotomas), and other types of vision defects.

In some cases, your doctor may suggest a magnetic resonance imaging (MRI) scan. This imaging test can help identify issues such as tumors, sinus problems and fractures. MRI can also detect changes related to multiple sclerosis in the brain’s white or grey matter.

A computed tomography (CT) scan without contrast is sometimes recommended if there’s a suspicion that the optic atrophy was caused by a fracture.

Optical Coherence Tomography (OCT) is another type of imaging test that can show a thinning of the layer of nerve fibers in the retina, a tell-tale sign of optic atrophy.

An ultrasound of the eye (B-scan) is recommended in cases where a tumor might be causing the problem. It can also detect dilation of the nerve sheath in a condition called papilledema.

Blood glucose tests can be helpful in diagnosing diabetes or as a baseline level check before starting steroid therapy.

To investigate vascular causes of optic atrophy, blood pressure and cardiovascular examinations could be ordered. A Doppler ultrasound of the carotid arteries may be necessary in some cases to rule out blockages that could be causing the optic atrophy.

Vitamin B-12 levels may also need to be checked to rule out nutritional causes of optic atrophy.

Other laboratory tests could be conducted based on individuals’ circumstances. Tests might include checks for syphilis, lupus, Lyme disease, herpes simplex, and other conditions.

Electroretinography (ERG) is a test that measures the electrical responses of cells in the eyes to light, which may reveal abnormalities associated with optic atrophy.

A Visually Evoked Response/Visually Evoked Potential (VER/VEP) test might be conducted if optic neuritis is suspected. This test can reveal any delays in the transmission of visual information from the eye to the brain.

Finally, a test called Fundus Fluorescein Angiography (FFA) can be carried out in cases of retino-choroiditis and diabetic retinopathy. This test uses a special dye to highlight the blood vessels in the back of the eye to allow examination for defects.

Treatment Options for Optic Atrophy

At present, the ideal treatment for optic atrophy, which would involve the regeneration of damaged nerves, is unfortunately not available for patient use. Medications to treat optic atrophy have also proven mostly ineffective. The key to managing optic atrophy is to treat its root cause before significant damage occurs, in order to maintain useable eyesight. Once the condition is stabilized, devices to aid low vision may be suggested for certain individuals.

In some cases, strong medical anti-inflammatory treatment such as pulse intravenous methylprednisolone, have been used to treat conditions like optic neuritis, a type of inflammation that damages the optic nerve, and traumatic optic neuropathy, injury to the optic nerve, with some success. Additionally, medications such as beta-interferons and glatiramer acetate may be used to treat multiple sclerosis and related optic neuritis to reduce the occurrence of visible damage on MRI scans as well as the number of times the condition reoccurs.

There is hope for the future with promising treatments such as stem cell therapy. For neuronal disorders, which involve nerve cells of the brain, stem cell treatment may become key. In this type of therapy, neural progenitor cells, which can develop into several different types of nerve cells, can be delivered to the gel-like substance that fills the eye. From here, these cells can incorporate into the layer of the retina where the nerve cells are located. These cells can then activate genes that build nerve fibers and travel into the optic nerve itself to stimulate the regeneration of the damaged parts of the nerve.

What else can Optic Atrophy be?

If a doctor suspects you have optic atrophy, they may need to rule out other conditions that can resemble it. These conditions include:

• Optic Nerve Pit: A birth defect resulting in a greyish depression on the optic nerve head. It could cause fluid build-up under the retina in nearly half of the cases.
• Myelinated Nerve Fibers: Sometimes, nerve fiber bundles extend into the retina. They visually appear as white feathery patches that may hide the disc margin and vessels, possibly enlarging the blind spot.
• Optic Disc Drusen: These are tiny calcium deposits within the optic nerve head. Though usually symptomless, they could blur vision occasionally. They are bilateral in about 75% of the cases, can enlarge and calcify, or regress, leaving a pale disc. They can also cause the filling of the optic cup and unusual branching of blood vessels.
• Optic Nerve Hypoplasia: This is a common optic nerve anomaly where the nerve appears notably tiny due to the lack of axons passing through the optic nerve head.
• Brighter-Than-Normal Luminosity: Excessive illumination from the ophthalmoscope or slit lamp could make the disc look pale, mimicking optic atrophy.

By taking these possible conditions into consideration, a doctor can ensure the correct diagnosis and treatment.

What to expect with Optic Atrophy

The future of one’s vision when dealing with optic atrophy, a condition where the optic nerve (which sends visuals from your eye to your brain) is damaged, largely depends on the degree to which the nerve fibers, known as axons, are lost. In cases of partial optic atrophy, the visual impairment could range from mild to moderate. There might even be cases where there is no noticeable decrease in sharpness of vision but a reduction in the field of vision. On the other hand, if the optic atrophy is total, meaning all of the axons are damaged, the vision prognosis is not favorable.

However, early and aggressive treatment in conditions such as optic neuritis (an inflammation of the optic nerve often caused by an autoimmune response) and toxic or nutritional optic neuropathy (a group of medical disorders caused by damage from harmful substances or nutritional deficiencies), may possibly result in almost a complete recovery of vision.

Possible Complications When Diagnosed with Optic Atrophy

Optic atrophy isn’t a disease on its own but it’s a symptom that points to several other conditions. Hence, any complications are actually tied to the related underlying condition, rather than the optic atrophy. The main complication linked directly to optic atrophy is loss of vision.

Common Complication:

• Vision Loss

Recovery from Optic Atrophy

When your vision has stabilized, you can start using certain measures to help it improve or cope with your situation. These could include using aids designed for those with low vision, changes to your working environment, occupational rehabilitation (which is a process to help you get back to work), and trying to avoid anything that might worsen your vision.

Preventing Optic Atrophy

It’s important that everyone understands the value of a healthy lifestyle. Bad eating habits and addictions can sometimes lead to damage to the optic nerve (the nerve that connects our eyes to our brain), but this is often preventable. We need to teach everyone, especially those who might be more at risk, about this. Additionally, people who have certain health conditions should be made aware of any signs that might indicate that their optic nerve is becoming damaged. This way, they can identify potential problems early.