Optic neuropathy

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Optic neuropathy
Other namesOptic nerve disorder
Specialty Neurology, Ophthalmology
Symptoms Vision loss, reduced color vision, blurred vision
Complications Permanent vision loss, blindness
Usual onsetSudden or gradual
DurationVariable, depending on cause
TypesIschemic optic neuropathy, optic neuritis, traumatic optic neuropathy, hereditary optic neuropathy
CausesVascular issues, inflammation, trauma, toxins, genetic mutations (e.g., Leber's hereditary optic neuropathy)
Risk factors Age, smoking, cardiovascular disease, genetic predisposition
Diagnostic method Clinical evaluation, visual field tests, optical coherence tomography, MRI
Differential diagnosis Glaucoma, retinal disease, brain lesions
PreventionManaging risk factors like blood pressure, avoiding smoking, regular eye exams
TreatmentAddressing underlying cause (e.g., steroids for inflammation, [1] surgery for trauma), vision rehabilitation
Medication Corticosteroids (for optic neuritis), other medications depending on the cause
Prognosis Variable; some cases recover, others lead to permanent vision loss
FrequencyCommon in individuals with risk factors (e.g., older adults, smokers)
DeathsNone directly from optic neuropathy, but complications from underlying causes (e.g., stroke) can be fatal

Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain.

Contents

Damage and death of these nerve cells, or neurons, leads to characteristic features of optic neuropathy. The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. A pale disc is characteristic of long-standing optic neuropathy. In many cases, only one eye is affected and a person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye.

Optic neuropathy is often called optic atrophy, to describe the loss of some or most of the fibers of the optic nerve.

Signs and symptoms

The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. In many cases, only one eye is affected and the person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. People may also engage in "eccentric viewing" using peripheral vision to compensate for central vision loss characteristic in genetic, toxic, or nutritional optic neuropathy.

On examination of the fundus, a pale optic disc is characteristic of long-standing optic neuropathy.

Causes

The optic nerve contains axons of nerve cells that emerge from the retina, leave the eye at the optic disc, and go to the visual cortex where input from the eye is processed into vision. There are 1.2 million optic nerve fibers that derive from the retinal ganglion cells of the inner retina. [2] Damage to the optic nerve can have different causes:

Ischemic

In ischemic optic neuropathies, there is insufficient blood flow (ischemia) to the optic nerve. The anterior optic nerve is supplied by the short posterior ciliary artery and choroidal circulation, while the retrobulbar optic nerve is supplied intraorbitally by a pial plexus, which arises from the ophthalmic artery, internal carotid artery, anterior cerebral artery, and anterior communicating arteries. Ischemic optic neuropathies are classified based on the location of the damage and the cause of reduced blood flow if known. [3]

Inflammatory

Optic neuritis is inflammation of the optic nerve, which is associated with swelling and destruction of the myelin sheath covering the optic nerve. Young adults, usually females, are most commonly affected. Symptoms of optic neuritis in the affected eye include pain on eye movement, sudden loss of vision, and decrease in color vision (especially reds). Optic neuritis, when combined with the presence of multiple demyelinating white matter brain lesions on MRI, is suspicious for multiple sclerosis.

Several causes and clinical courses are possible for the optic neuritis. It can be classified in:

Medical examination of the optic nerve with an ophthalmoscope may reveal a swollen optic nerve, but the nerve may also appear normal. Presence of an afferent pupillary defect, decreased color vision, and visual field loss (often central) are suggestive of optic neuritis. Recovery of visual function is expected within 10 weeks. However, attacks may lead to permanent axonal loss and thinning of the retinal nerve fiber layer.

Compressive

Tumors, infections, and inflammatory processes can cause lesions within the orbit and, less commonly, the optic canal. These lesions may compress the optic nerve, resulting optic disc swelling and progressive visual loss. Implicated orbital disorders include optic gliomas, meningiomas, hemangiomas, lymphangiomas, dermoid cysts, carcinoma, lymphoma, multiple myeloma, inflammatory orbital pseudotumor, and thyroid ophthalmopathy. Patients often have bulging out of the eye (proptosis) with mild color deficits and almost normal vision with disc swelling.

Infiltrative

The optic nerve can be infiltrated by a variety of processes, including tumors, inflammation, and infections. Tumors that can infiltrate the optic nerve can be primary (optic gliomas, capillary hemangiomas, and cavernous hemangiomas) or secondary (metastatic carcinoma, nasopharyngeal carcinoma, lymphoma, and leukemia). The most common inflammatory disorder that infiltrates the optic nerve is sarcoidosis. Opportunistic fungi, viruses, and bacteria may also infiltrate the optic nerve. The optic nerve may be elevated if the infiltration occurs in the proximal portion of the nerve. The appearance of the nerve on examination depends on the portion of the nerve that is affected.

Traumatic

The optic nerve can be damaged when exposed to direct or indirect injury. Direct optic nerve injuries are caused by trauma to the head or orbit that crosses normal tissue planes and disrupts the anatomy and function of the optic nerve; e.g., a bullet or forceps that physically injures the optic nerve. Indirect injuries, like blunt trauma to the forehead during a motor vehicle accident, transmit force to the optic nerve without transgressing tissue planes. This type of force causes the optic nerve to absorb excess energy at the time of impact. The most common site of injury of the optic nerve is the intracanalicular portion of the nerve. Deceleration injuries from motor vehicle or bicycle accidents account for 17 to 63 percent of cases. Falls are also a common cause, and optic neuropathy most commonly occurs when there is a loss of consciousness associated with multi-system trauma and serious brain injury. In less than three percent of patients, an orbital hemorrhage after an injection behind the eye (retrobulbar block) can cause injury to the optic nerve, but this is readily manageable if it does not involve direct optic nerve injury and is caught early. The role of high-dose steroids and orbital decompression in treating these patients is controversial and, if administered, must be done very soon after injury with minimal effects. In patients with an orbital fracture, vomiting or nose blowing can force air into the orbit and possibly compromise the integrity of the optic nerve.

Mitochondrial

Mitochondria play a central role in maintaining the life cycle of retinal ganglion cells because of their high energy dependence. Mitochondria are made within the central somata of the retinal ganglion cell, transported down axons, and distributed where they are needed. Genetic mutations in mitochondrial DNA, vitamin depletion, alcohol and tobacco abuse, and use of certain drugs can cause derangements in efficient transport of mitochondria, which can cause a primary or secondary optic neuropathy. [5]

Nutritional

A nutritional optic neuropathy may be present in a patient with obvious evidence of under-nutrition (weight loss and wasting), but also malnutrition due to picky eating as in autism. [6] Months of depletion are usually necessary to deplete body stores of most nutrients. Undernourished patients often have many vitamin and nutrient deficiencies and have low serum protein levels. However, the optic neuropathy associated with pernicious anemia and vitamin B12 deficiency can even be seen in well-nourished individuals. Gastric bypass surgery may also cause a vitamin B12 deficiency from poor absorption.

Patients who have nutritional optic neuropathy may notice that colors are not as vivid or bright as before and that the color red is washed out. This normally occurs in both eyes at the same time and is not associated with any eye pain. They might initially notice a blur or fog, followed by a drop in vision. While vision loss may be rapid, progression to blindness is unusual. These patients tend to have blind spots in the center of their vision with preserved peripheral vision. In most cases, the pupils continue to respond normally to light.

Toxins

Many heavy metals and toxicants can cause optic neuropathy:

Hereditary

The inherited optic neuropathies typically manifest asa symmetric bilateral central visual loss. Optic nerve damage in most inherited optic neuropathies is permanent and progressive.

Treatments

While optic neuropathy cannot be outright cured, there are surgical options to alleviate pain and symptoms associated with such diseases. The Endoscopic Endonasal Approach method (EEA) is a method of relieving pressure associated with tumors formed in the brain that press upon the optic nerve. It is a minimally invasive surgery.

In genetic and developmental causes of optic neuropathy, no surgeries have been proven treatments.

See also

Related Research Articles

<span class="mw-page-title-main">Optic neuritis</span> Inflammation of the optic nerve

Optic neuritis describes any condition that causes inflammation of the optic nerve; it may be associated with demyelinating diseases, or infectious or inflammatory processes.

<span class="mw-page-title-main">Optic nerve</span> Second cranial nerve, which connects the eyes to the brain

In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.

<span class="mw-page-title-main">Papilledema</span> Swelling of the eyes optic disc due to high intracranial pressure

Papilledema or papilloedema is optic disc swelling that is caused by increased intracranial pressure due to any cause. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare.

The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.

<span class="mw-page-title-main">Leber's hereditary optic neuropathy</span> Mitochondrially inherited degeneration of retinal nerve cells

Leber's hereditary optic neuropathy (LHON) is a mitochondrially inherited degeneration of retinal ganglion cells (RGCs) and their axons that leads to an acute or subacute loss of central vision; it predominantly affects young adult males. LHON is transmitted only through the mother, as it is primarily due to mutations in the mitochondrial genome, and only the egg contributes mitochondria to the embryo. Men cannot pass on the disease to their offspring. LHON is usually due to one of three pathogenic mitochondrial DNA (mtDNA) point mutations. These mutations are at nucleotide positions 11778 G to A, 3460 G to A and 14484 T to C, respectively in the ND4, ND1 and ND6 subunit genes of complex I of the oxidative phosphorylation chain in mitochondria.

Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision caused by damage to the anterior portion of the optic nerve as a result of insufficient blood supply (ischemia). This form of ischemic optic neuropathy is generally categorized as two types: arteritic AION, in which the loss of vision is the result of an inflammatory disease of arteries in the head called temporal arteritis, and non-arteritic AION, which is due to non-inflammatory disease of small blood vessels. It is in contrast to posterior ischemic optic neuropathy, which affects the retrobulbar portion of the optic nerve.

Posterior ischemic optic neuropathy (PION) is a medical condition characterized by damage to the retrobulbar portion of the optic nerve due to inadequate blood flow (ischemia) to the optic nerve. Despite the term posterior, this form of damage to the eye's optic nerve due to poor blood flow also includes cases where the cause of inadequate blood flow to the nerve is anterior, as the condition describes a particular mechanism of visual loss as much as the location of damage in the optic nerve. In contrast, anterior ischemic optic neuropathy (AION) is distinguished from PION by the fact that AION occurs spontaneously and on one side in affected individuals with predisposing anatomic or cardiovascular risk factors.

<span class="mw-page-title-main">Ischemic optic neuropathy</span> Dysfunction of the optic nerve due to lack of blood flow

Ischemic optic neuropathy (ION) is the loss of structure and function of a portion of the optic nerve due to obstruction of blood flow to the nerve. Ischemic forms of optic neuropathy are typically classified as either anterior ischemic optic neuropathy or posterior ischemic optic neuropathy according to the part of the optic nerve that is affected. People affected will often complain of a loss of visual acuity and a visual field, the latter of which is usually in the superior or inferior field.

Arteritic anterior ischemic optic neuropathy is vision loss that occurs in giant cell arteritis. Temporal arteritis is an inflammatory disease of medium-sized blood vessels that happens especially with advancing age. AAION occurs in about 15-20 percent of patients with temporal arteritis. Damage to the blood vessels supplying the optic nerves leads to insufficient blood supply (ischemia) to the nerve and subsequent optic nerve fiber death. Most cases of AAION result in nearly complete vision loss first to one eye. If the temporal arteritis is left untreated, the affected eye will likely suffer vision loss as well within 1–2 weeks. Arteritic AION (AAION) falls under the general category of anterior ischemic optic neuropathy (AION), which also includes non-arteritic AION (NAION). AAION is considered an eye emergency, immediate treatment is essential to rescue remaining vision.

Dominant optic atrophy (DOA), or autosomal dominant optic atrophy (ADOA), (Kjer's type) is an autosomally inherited disease that affects the optic nerves, causing reduced visual acuity and blindness beginning in childhood. However, the disease can seem to re-present a second time with further vision loss due to the early onset of presbyopia symptoms (i.e., difficulty in viewing objects up close). DOA is characterized as affecting neurons called retinal ganglion cells (RGCs). This condition is due to mitochondrial dysfunction mediating the death of optic nerve fibers. The RGCs axons form the optic nerve. Therefore, the disease can be considered of the central nervous system. Dominant optic atrophy was first described clinically by Batten in 1896 and named Kjer’s optic neuropathy in 1959 after Danish ophthalmologist Poul Kjer, who studied 19 families with the disease. Although dominant optic atrophy is the most common autosomally inherited optic neuropathy (i.e., disease of the optic nerves), it is often misdiagnosed.

Toxic and nutritional optic neuropathy is a group of medical disorders defined by visual impairment due to optic nerve damage secondary to a toxic substance and/or nutritional deficiency. The causes of these disorders are various, but they are linked by shared signs and symptoms. In several of these disorders, both toxic and nutritional factors play a role, acting synergistically.

<span class="mw-page-title-main">Optic disc drusen</span> Medical condition

Optic disc drusen (ODD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells. ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies.

<span class="mw-page-title-main">Chiasmal syndrome</span> Set of signs and symptoms that are associated with lesions of the optic chiasm

Chiasmal syndrome is the set of signs and symptoms that are associated with lesions of the optic chiasm, manifesting as various impairments of the affected's visual field according to the location of the lesion along the optic nerve. Pituitary adenomas are the most common cause; however, chiasmal syndrome may be caused by cancer, or associated with other medical conditions such as multiple sclerosis and neurofibromatosis.

<span class="mw-page-title-main">Blurred vision</span> Medical condition

Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details.

An optic nerve melanocytoma is a tumor made up of melanocytes and melanin. Melanocytomas are typically a benign meaning they can grow, but rarely transform into a malignancy. Even so, local growth can affect adjacent tissues. Most optic nerve melanocytomas are small, black, and do not grow. Most optic nerve tumors are gliomas that occur somewhere along the anterior visual pathway.

Autoimmune optic neuropathy (AON), sometimes called autoimmune optic neuritis, may be a forme fruste of systemic lupus erythematosus (SLE) associated optic neuropathy. AON is more than the presence of any optic neuritis in a patient with an autoimmune process, as it describes a relatively specific clinical syndrome. AON is characterized by chronically progressive or recurrent vision loss associated with serological evidence of autoimmunity. Specifically, this term has been suggested for cases of optic neuritis with serological evidence of vasculitis by positive ANA, despite the lack of meeting criteria for SLE. The clinical manifestations include progressive vision loss that tends to be steroid-responsive and steroid dependent.

Mitochondrial optic neuropathies are a heterogenous group of disorders that present with visual disturbances resultant from mitochondrial dysfunction within the anatomy of the Retinal Ganglion Cells (RGC), optic nerve, optic chiasm, and optic tract. These disturbances are multifactorial, their aetiology consisting of metabolic and/or structural damage as a consequence of genetic mutations, environmental stressors, or both. The three most common neuro-ophthalmic abnormalities seen in mitochondrial disorders are bilateral optic neuropathy, ophthalmoplegia with ptosis, and pigmentary retinopathy.

<span class="mw-page-title-main">Visual pathway lesions</span> Visual maladies

The visual pathway consists of structures that carry visual information from the retina to the brain. Lesions in that pathway cause a variety of visual field defects. In the visual system of human eye, the visual information processed by retinal photoreceptor cells travel in the following way:
Retina→Optic nerve→Optic chiasma →Optic tract→Lateral geniculate body→Optic radiation→Primary visual cortex

Diabetic papillopathy is an ocular complication of diabetes mellitus characterized by optic disc swelling and edema of optic nerve head. The condition may affect both type 1 and type 2 diabetic patients.

Non-arteritic anterior ischemic optic neuropathy (NAION) is a medical condition characterized by loss of vision caused by damage to the optic nerve as a result of ischemia, or insufficient blood supply. The key symptom of NAION is optic disc swelling, which typically resolves within 2 months, but often leads to optic atrophy. The likelihood of vision improvement after developing this condition is low.

References

  1. ↑ Stunkel L, Van Stavern GP (2018). "Steroid Treatment of Optic Neuropathies". Asia-Pacific Journal of Ophthalmology. 7 (4). Philadelphia, Pa.: 218–228. doi: 10.22608/APO.2018127 . PMID   29962119.
  2. ↑ Sadun AA (August 1986). "Neuroanatomy of the human visual system: Part I Retinal projections to the LGN and pretectum as demonstrated with a new method". Neuro-Ophthalmology. 6 (6): 353–361. doi:10.3109/01658108609016475.
  3. ↑ Miller NR, Newman NJ, Biousse V, Kerrison JB (2000). "Ischemic optic neuropathies". Walsh & Hoyt's Clinical Neuro-Ophthalmology: The Essentials (2nd ed.). Lippincott Williams & Wilkins. pp. 162–175. ISBN   978-0-7817-6379-0.
  4. ↑ Petzold A, Plant GT (2014). "Diagnosis and classification of autoimmune optic neuropathy". Autoimmunity Reviews. 13 (4–5): 539–545. doi:10.1016/j.autrev.2014.01.009. PMID   24424177.
  5. ↑ Carelli V, Ross-Cisneros FN, Sadun AA (January 2004). "Mitochondrial dysfunction as a cause of optic neuropathies". Progress in Retinal and Eye Research. 23 (1): 53–89. doi:10.1016/j.preteyeres.2003.10.003. PMID   14766317. S2CID   15862778.
  6. ↑ Gaier ED, Jaimes C, Gise RA, Armstrong-Javors AE, Kadzielski SM (August 2024). Cabot RC, Rosenberg ES, Dudzinski DM, Baggett MV, Tran KM, Sgroi DC, Shepard JA, McDonald EK, Corpuz (eds.). "Case 25-2024: A 12-Year-Old Boy with Autism and Decreased Vision". The New England Journal of Medicine. 391 (7): 641–650. doi:10.1056/NEJMcpc2309726. PMID   39141857.
  7. ↑ Baj J, Forma A, Kobak J, Tyczyńska M, Dudek I, Maani A, et al. (March 2022). "Toxic and Nutritional Optic Neuropathies-An Updated Mini-Review". International Journal of Environmental Research and Public Health. 19 (5): 3092. doi: 10.3390/ijerph19053092 . PMC   8910489 . PMID   35270784.
  8. ↑ Oostra RJ, Bolhuis PA, Wijburg FA, Zorn-Ende G, Bleeker-Wagemakers EM (April 1994). "Leber's hereditary optic neuropathy: correlations between mitochondrial genotype and visual outcome". Journal of Medical Genetics. 31 (4): 280–286. doi:10.1136/jmg.31.4.280. PMC   1049799 . PMID   8071952.
  9. ↑ "Berk-Tabatznik syndrome". Genetic and Rare Diseases Information Center (GARD). U.S. National Institutes of Health. Retrieved 28 September 2013.

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