Optic Atrophy (Optic Neuropathy)

Optic Neuropathy or Optic Atrophy or Optic Nerve Head Pallor is the damage to the optic nerves. Ischemic optic neuropathy is where blood doesn’t flow to the eye nerve resulting in degeneration or damage to the optic nerve.

damage of the optic neurons also called optic nerve located between the lateral geniculate body and retinal ganglion cells lead to the development of certain symptoms for optic atrophy.

Optic neuropathy is not a disease rather is a sign of a serious condition. Resulting from various forms of pathologies, optic atrophy leads to severe vision problems and often blindness.

Optic Nerve Hypoplasia

It is a congenital condition in which the optic nerve remains underdeveloped, mostly at the time of birth. A routine eye checkup is recommended to diagnose the condition.

Symptoms

  • Blurred vision
  • Decreased brightness in one eye
  • Change in the optic disc
  • Poor constriction of the pupil in light
  • Loss of vision from retinal detachment
  • Flu-like infections in children
  • Eye pain

Types

1 – Aetiological

  • Primary: Occurs without antecedent swelling of the optic nerve
  • Secondary: Long-standing swelling of the optic nerve
  • Consecutive: Caused by disease of the inner retina or its blood supply

2 – Extent

  • Partial: Concentric contraction of visual field with or without scotoma.
  • Total: Pupils dilated and are non-reacting

3 – Clinical/Ophthalmological

  • Cavernous/glaucomatous: Deep and wide cupping of optic disc and nasal shifting of blood vessels

Central Retinal Vein Occlusion (CRVO)

It is the blockage of the central retinal vein that fills excess fluid into the retina responsible for the central vision. If the fluid gets collected in the area, the macula is affected resulting in blurry central vision. CRVO is perhaps the most common retinal vascular disorder.

Causes

Optic Neuritis

It results in inflammations in the nerve of the optic and results in the damage and swelling of ‘myelin sheath’ (sheath covering the optic nerve). The symptoms for this include:

  • Pain while moving the eye
  • Loss of vision suddenly
  • Loss of color vision

If one observes the optic neuritis symptoms, it might have the demyelinating brain lesions and multiple sclerosis. An eye examination using an ophthalmoscope shows the exact condition of the nerve. The loss of visuals and several papillary defects suggest optic neuritis. Nevertheless, a patient may recover within ten weeks of this condition.

Ischemic Optic Neuropathy

It occurs due to ischemia or low flowing of blood to the optic nerve. This situation differs by the damage location along the factors responsible for blood loss.

Anterior Ischemic Optic Neuropathy

AION (anterior ischemic optic neuropathy) involves diseases that damage the optic nerve hea, therefore,e causing swelling of the optic disc. It can also cause rapid and sudden visual loss in one eye. Most AION cases are non-arteritic AION.

NAION is a pain-free vision loss that mostly occurs after awakening and may last for several hours or even days. The pathophysiology of non-arteritic anterior ischemic optic neuropathy is not known but is related to impoverished circulation in optic nerve head.

NAIONs may result in elevated intraocular pressure caused by eye surgery, hypercoagulable states, diabetes mellitus, high cholesterol, a drop in one’s blood pressure due to eye surgery or acute glaucoma (glaucomatous optic neuropathy). In rare cases, Erectile dysfunction drugs, interferon-alpha, and amiodarone occur.

Posterior Ischemic Neuropathy

This condition occurs when there is a sudden loss of vision without showing any signs of the swelling of the disk before.  Posterior ischemic optic neuropathy can occur in people with serious hypotension conditions.

Radiation Optic Neuropathy

Various Ischemic factors cause this condition when the orbit and the brain are given the therapy including radiations anywhere in nine years. It also causes radiation retinopathy (retina damage) leading to vision loss. Optic neuropathy can also occur after the treatment for Hepatitis C virus too.

Traumatic Optic Neuropathy

Various accidents or severe falls can drain the consciousness resulting in varying traumas and injury to the brain.

In rare conditions, an injection for orbital hemorrhage given behind the eye can result in trauma, damaging the optic nerve. But it is curable if detected early. Those who suffer from an orbital fracture can be a victim of optic nerve damage. Blowing nose or vomiting injects into the air causing damage to optic nerve.

Infiltrative Optic Neuropathy

Tumors and infections destroy the optic nerve. Tumors can be of any type including capillary hemangiomas, cavernous hemangiomas and optic gliomas which come under the primary one’s. the seconday section has leukemia, nasopharyngeal, carcinoma and lymphoma.

Sarcoidosis disorder affects the optic nerve which is a common type of inflammatory disorder.

Compressive Optic Neuropathy

The optic nerve gets compresses due to any Infections, tumors or inflammatory processes leading to swelling and increasing loss in the vision. There are several orbital disorders including:

  • Optic gliomas
  • Hemangiomas
  • Thyroid ophthalmology
  • Lymphomas
  • Carcinomas
  • Dermoid cysts
  • Meningiomas
  • Inflammatory orbital pseudotumor

People may also suffer from bulging of the eye affect also called proptosis with color deficiencies.

Mitochondrial Optic Neuropathy

Due to the high energy requirements, mitochondria help manage the operations of the retinal ganglion cells. The transportation of mitochondria is disturbed by factors including depletion of vitamin, genetic factors, abuse of drugs etc. leading to any type of optic atrophy.

Toxic Optic Neuropathies

These neuropathies occur from the intoxication of several substances including ethylene glycol, methanol, tobacco or ethambutol.

Nutritional Optic Neuropathies

People suffering from low levels of vitamin and protein may develop optic atrophy. The gastric bypass surgery might lower down the levels of vitamin B12. People may also have vision loss and blindness.

Optic Hereditary Neuropathies

Optic hereditary neuropathies result in vision loss. Many cases have been found where it permanently damages the optic nerve. Some of the neuropathies are dominant atrophy, Leber’s hereditary optic neuropathy and Behr’s syndrome.

Optic Nerve Regeneration

As of now, optic nerve regeneration is only possible in lower vertebrates including fishes and frogs. In mammals, the retinal ganglion cells can generate their axons completely.

Risks Factors

  • Trauma
  • Hereditary conditions
  • Toxic or nutritional problems
  • Vascular diseases (Blood vessel disorders)
  • Glaucoma (A disease of the eyes where the fluid pressure within the eye rises)
  • Diabetes
  • Compressive lesion of the optic nerve
  • Arteritic optic neuropathy
  • Ophthalmoplegia (Paralysis of the eye muscles)

Diagnosis

An eye test is vital for diagnosing optic atrophy which includes medical history, color vision, side vision and pupil reaction. The ophthalmologist (eye specialist) will look for the pale atrophy optic nerve through an ophthalmoscope. Additional tests like MRI of the orbits, brain and blood tests can be done. Other tests for diagnosis can also be conducted to know the condition of the colored vision. The tests are:

  • FLAIR (fluid-attenuated inversion recovery) test
  • Visually revoked response
  • CT scans
  • Testing of visual field
  • Examination of cranial nerve
  • Recovery test of photostress
  • Pulfrich phenomenon
  • Tests for pupil light reflex
  • TORCH panel test
  • electroretinogram

Optic Atrophy differential diagnosis

The differential diagnosis can help in actually knowing the type of treatment one requires. It includes isolating its symptoms these conditions including:

  • Optic nerve hypoplasia
  • Tilted disc
  • Optic nerve pit
  • Myelinated nerve fibers
  • Optic disc drusen
  • Scleral crescent

Treatment

Optic Neuritis Treatment Trials (ONTT): Treatment is done using intravenous steroids, oral steroids or placebo which have proven to manage cases of artistic anterior ischemic optic neuropathy. Patients on medications are given IV steroids for three days followed by 11 days of oral steroids.

As of now, there is no specific treatment for optic atrophy. It is often impossible to go back once regeneration process begins.

Patients can also be water-soluble bile supplements of vitamin like Nascobal which prove important for the metabolism of the normal and synthesis of the DNA. But researches have been looking forward to the therapy of stem cell for amending the condition. The optimum way to handle current scenario is diagnosing optic atrophy as instant as possible.

Prevention

  • Elder people need to be careful with the blood pressure
  • Prevent injury to the face
  • Avoid consumption of home-brewed alcohol
  • Avoid eating tobacco
  • Refrain from vigorous exercises
  • Take proper nutrition and hydration
  • Oral medications (Teriflunomide, Fingolimod, and Dimethyl Fumarate)

References

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